[{"data":1,"prerenderedAt":531},["ShallowReactive",2],{"guide-facebook-custom-audience-not-populating":3},{"id":4,"title":5,"answer":6,"authorId":7,"body":8,"category":422,"ctaVariant":423,"dataset":422,"description":424,"examples":425,"extension":426,"faqs":427,"heroImage":452,"intro":453,"meta":454,"navigation":456,"path":457,"publishedAt":458,"seo":459,"sources":460,"stats":505,"stem":529,"updatedAt":458,"__hash__":530},"blog\u002Fblog\u002Ffacebook-custom-audience-not-populating.md","Custom Audience Not Populating? Fixes (2027)","A custom audience that will not populate usually comes down to a handful of causes, and the first is a reading error rather than a data error. Most often you are reading the size column instead of the status column: Meta hides the size for privacy while the audience is Ready. The rest are pixel or Conversions API events not reaching Meta, a retention window that has expired members out, a misformatted customer list, an audience still hashing, or one flagged under Meta's restricted-audience rules. Meta documents a 100-customer minimum for a customer list file, but publishes no 1,000-person delivery minimum anywhere, so stop diagnosing against that number.","likit-sae-lee",{"type":9,"value":10,"toc":404},"minimark",[11,16,20,23,26,29,33,36,39,42,60,63,67,70,76,82,88,91,96,99,111,118,121,124,128,131,134,137,140,149,153,156,159,162,165,168,186,190,193,200,203,206,209,212,216,219,222,225,228,231,235,238,241,244,248,251,254,262,265,269,272,380,383,387,390,393,401],[12,13,15],"h2",{"id":14},"start-by-killing-the-1000-user-myth","Start by killing the 1,000-user myth",[17,18,19],"p",{},"Search this problem and you will be told, confidently and repeatedly, that Meta needs roughly 1,000 people in a custom audience before it will deliver. It is worth being blunt about this: that number is folklore. No Meta Business Help Center page and no Meta for Developers page states a 1,000-person delivery minimum for a custom audience. Every source asserting it is a marketing blog or a forum answer quoting another marketing blog. If you are sitting on an audience of 640 people and refusing to launch because you are 360 short of a rule you read somewhere, you are stuck on a number Meta never published.",[17,21,22],{},"Here is what Meta does document. A customer list custom audience needs at least 100 customers, in a CSV or TXT file, including at least one main identifier. A lookalike audience's origin audience, the seed, must contain at least 100 members, and a value-based lookalike wants at least 100 unique conversions with 200 or more recommended. Those are the two real minimums, and note how narrow they are. The first is a file requirement for one audience type. The second is a seeding requirement for a different product entirely. Neither is a general delivery gate, and neither should be transplanted into \"my website custom audience needs 100 people to run.\"",[17,24,25],{},"Does a small audience hurt delivery? Meta guards against it in the one place marketers rarely look. The Marketing API refuses removals that would push an audience too low, and the error reference carries error 200, subcode 1870047: \"Audience Size too Low: You cannot remove users from this audience because it will result in a low audience size and may result in under-delivery or non-delivery of your ads.\" Read that carefully, because both the scope and the wording matter. Meta is blocking a shrink operation, and it says the result \"may\" under-deliver. It names the risk. It never names a threshold.",[17,27,28],{},"So the honest position, and the one that will actually get your campaign live, is this: Meta warns about the failure and publishes no figure. Stop diagnosing against 1,000. Diagnose against the states Meta actually shows you.",[12,30,32],{"id":31},"read-the-status-column-not-the-size-column","Read the status column, not the size column",[17,34,35],{},"Before you touch anything, check whether you have a data problem or a reading problem, because a surprising share of \"not populating\" reports are the latter.",[17,37,38],{},"Estimated audience size and audience status are separate fields answering separate questions. On Meta's own troubleshooting page, estimated audience size in Audiences can display Unavailable or Populating even when the audience's status is Ready, because Meta sometimes cannot show the size for privacy reasons. An empty size box is not an empty audience. It is frequently just Meta declining to tell you a number.",[17,40,41],{},"That gives you a first diagnostic step that costs nothing:",[43,44,45,54,57],"ol",{},[46,47,48,49,53],"li",{},"Open Audiences and look at the ",[50,51,52],"strong",{},"status"," column. Populating, Ready, Outdated, or something else?",[46,55,56],{},"If status reads Ready, ignore the size box entirely.",[46,58,59],{},"Go into ad set creation in Ads Manager, select the audience, and read the estimate there. Meta says the size will show in ad creation.",[17,61,62],{},"If status is Ready and the ad set estimate looks sane, you never had a problem. Publish. If status is Ready and the ad set still shows nothing usable, then you have a real signal or retention issue, and the sections below are where to look. Do not re-upload the list, do not rebuild the rules, and do not delete and recreate the audience until you have done this. Rebuilding resets the clock on your own diagnosis and tells you nothing.",[12,64,66],{"id":65},"the-states-ads-manager-shows-and-what-each-one-means","The states Ads Manager shows, and what each one means",[17,68,69],{},"A customer list audience moves through a documented lifecycle after upload, and each label in the status column is a different instruction to you.",[17,71,72,75],{},[50,73,74],{},"Populating."," Meta is hashing and matching. This takes a few minutes depending on list size. This is the normal state immediately after upload and it is not a problem.",[17,77,78,81],{},[50,79,80],{},"Ready."," The audience is usable. Size may still read Unavailable, per the section above.",[17,83,84,87],{},[50,85,86],{},"Outdated."," This one gets missed. A customer list audience shows Outdated when the list has not been updated in over 30 days, and Meta says that may impact ad delivery. If you uploaded a list six months ago and have been retargeting it ever since, that audience has been quietly flagged as stale the whole time. It has members, but it is not healthy. Refresh the list.",[17,89,90],{},"Those three are what the Audiences table gives you. That is the whole vocabulary of the status column, which matters because the next two things on this page happen without a label to read.",[92,93,95],"h3",{"id":94},"what-the-api-returns-and-what-happens-silently","What the API returns, and what happens silently",[17,97,98],{},"Two more states exist that a user-interface advertiser will never see spelled out in that column.",[17,100,101,102,105,106,110],{},"The first is a ",[50,103,104],{},"flagged audience",". Meta restricts audiences that suggest information not permitted under its terms, and a flagged audience cannot be used for new campaigns. Through the Marketing API this surfaces as ",[107,108,109],"code",{},"operation_status"," 471. In Ads Manager it surfaces as an audience that simply will not go into a new campaign, which is the section below.",[17,112,113,114,117],{},"The second is an ",[50,115,116],{},"expiring audience",". Customer file custom audiences that have not been used in any active ad set in over two years are flagged for deletion on a rolling basis, and using the audience in an active ad set counts as an instruction to keep it. Nothing announces this to you. If you are reviving a dormant account, an audience you remember having may be on its way out.",[17,119,120],{},"If you work in Ads Manager only, the practical translation is simple. Read the status column for Populating, Ready, and Outdated. For the other two, watch behaviour instead: an audience that will not attach to a new campaign is the flagged case, and an audience that quietly disappears from a long-dormant account is the expiring one.",[17,122,123],{},"Timing expectations are worth pinning down honestly here too. Meta's developer docs say changes to a custom audience usually take up to 24 hours, and that processing time grows with the number of records removed and the number of custom audiences in the account. That statement is scoped to API changes, not a promised user-interface populating time. For website audiences, Meta commits to nothing at all beyond saying that how soon you can use one depends on your website traffic and when you placed your Meta Pixel. Anyone quoting you a firm \"24 hours to populate\" for a website audience is extending a sentence past what it says.",[12,125,127],{"id":126},"your-pixel-fires-are-not-your-audience-size","Your pixel fires are not your audience size",[17,129,130],{},"This is the single biggest source of \"my audience is way too small\" panic, and the explanation is plain arithmetic.",[17,132,133],{},"A pixel fire is an event. An audience member is a person. One visitor browsing seven pages fires seven PageView events and contributes exactly one member. Meta's own worked example on the website-audience troubleshooting page takes 20,000 reported visitors averaging seven pages each and lands at roughly 2,857 unique visitors in the audience. That is a 7x compression before anything else happens.",[17,135,136],{},"Then the subtraction starts. Visitors must be Meta technologies users to count at all, so any traffic from people without an account, or logged out and unmatched, contributes nothing. Accounts that opted out of online behavioral advertising are excluded. And Meta states plainly on its website-audience page that the size of a website custom audience may decrease because it may not include events from some iOS 14 users. Notably, Meta adds that using it as a lookalike source does not affect the lookalike's size, which is a useful thing to know before you panic about a shrinking seed.",[17,138,139],{},"So if your analytics says 20,000 sessions and your audience says 2,000 people, that is not necessarily a broken pixel. That may be the documented behaviour. Compare against unique users in the retention window, not against sessions, pageviews, or event totals, and the gap usually stops looking like a failure.",[17,141,142,143,148],{},"If events genuinely are not arriving, that is a different problem with a different guide. Work through ",[144,145,147],"a",{"href":146},"\u002Fblog\u002Ffacebook-pixel-not-tracking","why a Meta pixel is not tracking"," before you conclude the audience is at fault, because an audience built on a pixel that never fires will look identical to one Meta is withholding the size of.",[12,150,152],{"id":151},"how-much-did-att-really-cost-you","How much did ATT really cost you?",[17,154,155],{},"Be careful here, because this is where confident numbers get invented.",[17,157,158],{},"The primary, web-side fact is Meta's own line: the size of a website custom audience may decrease because it may not include events from some iOS 14 users. Meta gives you a direction and no magnitude, and has never published one. Any figure claiming web retargeting pools fell by a specific percentage is unverifiable.",[17,160,161],{},"The closest usable number lives in a different domain and must be labelled as such. AppsFlyer reported in April 2025, four years after the framework launched, that 50% of users globally consent to tracking. That is vendor measurement data, mobile app scope, directional only. It tells you the app ecosystem's consent picture. It does not measure your website pixel pool, and it must never be turned into \"half your website audience disappeared.\"",[17,163,164],{},"So the practical takeaway is a routing decision. If browser-side signal is thin, the documented route back to a populating pool is server-side. Meta's Custom Audiences developer guide states that if conversion events are shared through the Conversions API, a website custom audience can be built without additional data uploads. CAPI events alone can build the audience, straight from Meta's own documentation.",[17,166,167],{},"Your instrument for whether those server events are matching to real people is Event Match Quality. It is scored 0 to 10 for website events sent through the Conversions API and calculated from the last 48 hours of data, so it responds to changes fast enough to iterate against. Meta ranks Email and Click ID as High priority parameters, and lists Phone number, Country, Birthdate, External ID and Browser ID among the Medium priority ones. Send more of the High priority ones. Meta does not publish a target score, so ignore anyone who tells you the magic number is six. Watch your own trend line instead.",[17,169,170,171,175,176,180,181,185],{},"Two companion guides go deeper than this page should: ",[144,172,174],{"href":173},"\u002Fblog\u002Ffacebook-conversions-api-setup","Facebook Conversions API setup"," for the implementation path, and ",[144,177,179],{"href":178},"\u002Fblog\u002Ffacebook-pixel-vs-conversions-api","Meta pixel vs Conversions API"," for the decision between them. If you run both, ",[144,182,184],{"href":183},"\u002Fblog\u002Fmeta-pixel-capi-deduplication","pixel and CAPI deduplication"," matters, because double-counted events distort what you think you are seeing.",[12,187,189],{"id":188},"retention-windows-expire-people-out-from-under-you","Retention windows expire people out from under you",[17,191,192],{},"An audience does not just fill. It drains. Membership is dynamic, and people who fall outside the window are removed automatically, without a notification and without anything appearing broken.",[17,194,195,196,199],{},"This section carries a freshness trap that catches experienced buyers, so read the current numbers rather than the ones you remember. Website custom audience retention: standard rules look back up to 180 days, and Meta pixel event rules can look back up to 180 days, ",[50,197,198],{},"or 2 years for purchase events",". That 730-day purchase window is real and now carried on Meta's own help page. If your mental model is a flat 180-day ceiling, it is out of date.",[17,201,202],{},"What happened to the audiences that already existed is a different question, and here the documentation runs out. The 2-year purchase window is confirmed on Meta's own help page. Whether an existing 180-day purchase audience was migrated onto it, and whether that migration could be declined, is not documented anywhere Meta publishes. So do not trust your memory and do not trust a blog. Open your own audience and read its retention setting, which is the only version of this fact that governs your account.",[17,204,205],{},"Engagement audiences drain on a different clock. For the Instagram professional account source, retention tops out at 365 days, and membership is dynamic, so people who do not re-engage inside the window are removed automatically. Be careful generalising that figure: 365 days is verified for the Instagram account source specifically, and the other engagement sources (video, lead form, Instant Experience, Shopping, Events, Facebook Page) each need checking against their own help page rather than assuming one number covers them all.",[17,207,208],{},"Two more expiry mechanics you now know from the states section: a customer list untouched for 30 days flips to Outdated, and a customer file audience unused in an active ad set for two years enters the Expiring stage.",[17,210,211],{},"The behavioural fix is dull and effective. Put a recurring reminder against your core audiences. Refresh customer lists monthly rather than annually. Check retention settings after any Meta change lands, because a window that moves changes your pool size without touching your rules.",[12,213,215],{"id":214},"the-customer-list-problems-that-look-like-a-match-rate-problem","The customer list problems that look like a match-rate problem",[17,217,218],{},"When a list uploads and almost nothing matches, the instinct is to blame Meta's matching. Usually it is the file.",[17,220,221],{},"The country code is the big one. Meta matches on a global scale, so every phone number needs its country code even when every number on the list comes from the same country. Country gets the same treatment: it belongs in its own column, written as an ISO two-letter code, even when every row on the list is from one country. A list exported from a local checkout very often stores numbers in a purely local format, with no international prefix at all, and those rows are the ones that quietly fail. Full names must also be split into separate first name and last name columns, not left in a single field. The file must be CSV or TXT and include at least one main identifier, and it needs at least 100 customers.",[17,223,224],{},"Fix the columns before you touch anything else. And when someone offers you an average match rate, treat it with suspicion: Meta publishes no match-rate benchmark, so every circulating percentage is a vendor estimate dressed as a fact.",[17,226,227],{},"One structural cause sits outside the file entirely. A brand-new or newly linked ad account may wait a few weeks before it can create or share a customer list custom audience at all. If you are on a fresh account, a list that never populates may simply be an account that is not yet permitted to build one. All you can do is wait, and no amount of re-uploading shortens it.",[17,229,230],{},"Consent and legal basis are yours to establish, not Meta's to assume. Rules differ by jurisdiction, so check your own before you upload customer data.",[12,232,234],{"id":233},"the-audience-that-is-blocked-not-empty","The audience that is blocked, not empty",[17,236,237],{},"Since 2 September 2025, Meta proactively flags custom and lookalike audiences that suggest information not permitted under its terms. The examples Meta gives are specific health conditions such as arthritis or diabetes, and financial status such as credit score or high income. A flagged audience cannot be used for new campaigns, and through the Marketing API it returns operation_status 471. A flagged seed also poisons any lookalike built on top of it.",[17,239,240],{},"The reason this belongs in a \"not populating\" guide is that the symptom is indistinguishable if you are only watching size. The audience has members. It has a status. It will not run. A supplement brand with an audience named after a condition, or a finance brand with one named after income tier, hits this and can spend a week debugging a pixel that was never broken. There is a documented review-request path in Ads Manager and Audience Manager if you believe the flag is wrong.",[17,242,243],{},"The preventive habit is trivially cheap: name audiences after behaviour, not after inferred attributes. \"Purchasers 180d\" is a description of an event. \"Diabetes customers\" is an assertion about people, and that is precisely what the rule targets.",[12,245,247],{"id":246},"self-inflicted-starvation-rules-exclusions-and-video-sources","Self-inflicted starvation: rules, exclusions, and video sources",[17,249,250],{},"Sometimes the audience is small because you built it small.",[17,252,253],{},"A website custom audience can combine up to 5 rule sections, at least one of which must be inclusive, with up to 5 filters per event and up to 10 parameters per event. Stack enough exclusions inside those sections and you can starve a healthy pool without a single thing going wrong technically. When an audience looks thin, strip it back to one inclusive rule, read the size, then reintroduce exclusions one at a time and watch what each one costs you. That is a five-minute exercise that usually finds the culprit.",[17,255,256,257,261],{},"Video engagement audiences have a trap of their own that is worth knowing verbatim. An audience built from a video reused in an existing post pulls from that post's view count, not the campaign's. Meta's own example: a campaign recording over 200,000 views can build an audience from only 1,000 views. Two hundred thousand views, a thousand-person audience, and nothing malfunctioned. If your video audiences look absurdly small against your reported views, this is the first thing to check. Our guide to ",[144,258,260],{"href":259},"\u002Fblog\u002Ffacebook-engagement-custom-audience","engagement custom audiences"," covers the source-by-source detail.",[17,263,264],{},"One last honest note on limits, because Meta's own documentation contradicts itself here. The help centre says you can create up to 500 custom audiences per ad account. Meta's developer documentation instead lists per-type caps: 500 standard data file, 10,000 website, 200 mobile app, 500 lookalike. The two do not agree. If you are anywhere near a ceiling, trust the per-type numbers in the developer docs and expect the help centre figure to be a simplification, but check both against your own account before you plan around either.",[12,266,268],{"id":267},"a-diagnostic-order-that-saves-you-a-week","A diagnostic order that saves you a week",[17,270,271],{},"Work top to bottom and stop when it explains the symptom.",[273,274,275,288],"table",{},[276,277,278],"thead",{},[279,280,281,285],"tr",{},[282,283,284],"th",{},"Check",[282,286,287],{},"What you are ruling out",[289,290,291,300,308,316,324,332,340,348,356,364,372],"tbody",{},[279,292,293,297],{},[294,295,296],"td",{},"Read the status column, not size",[294,298,299],{},"A withheld size on a Ready audience",[279,301,302,305],{},[294,303,304],{},"Read the size inside ad set creation",[294,306,307],{},"The same, confirmed where Meta says it shows",[279,309,310,313],{},[294,311,312],{},"Status = Outdated?",[294,314,315],{},"A customer list untouched for 30 days",[279,317,318,321],{},[294,319,320],{},"Audience blocked from new campaigns? (the API returns operation_status 471)",[294,322,323],{},"A restricted audience that will never run",[279,325,326,329],{},[294,327,328],{},"Account age",[294,330,331],{},"A new account not yet allowed to build lists",[279,333,334,337],{},[294,335,336],{},"Retention setting on the audience",[294,338,339],{},"180 days vs 2 years for purchases, silent drainage",[279,341,342,345],{},[294,343,344],{},"Unique users vs pageviews",[294,346,347],{},"The 7x compression in Meta's own example",[279,349,350,353],{},[294,351,352],{},"Phone country codes, split names, CSV\u002FTXT, 100+ rows",[294,354,355],{},"Formatting mistaken for match rate",[279,357,358,361],{},[294,359,360],{},"Strip exclusions to one inclusive rule",[294,362,363],{},"Self-inflicted starvation",[279,365,366,369],{},[294,367,368],{},"Video source: post views or campaign views?",[294,370,371],{},"The 200,000-to-1,000 gap",[279,373,374,377],{},[294,375,376],{},"Event Match Quality trend, last 48 hours",[294,378,379],{},"Server events arriving but not matching",[17,381,382],{},"The sequencing matters more than any single row. Everything at the top is free and takes seconds. Everything at the bottom involves changing your setup. Most people start at the bottom, rebuild something, and lose a day.",[12,384,386],{"id":385},"what-to-fix-in-what-order","What to fix, in what order",[17,388,389],{},"Rebuild the reading first. Status, then ad set estimate. Then check the two silent killers, retention and staleness, because both drain an audience while every screen looks normal. Then confirm the file, because formatting explains more bad matches than matching does. Then, only then, look at signal.",[17,391,392],{},"If signal really is the problem, the fix is documented and unglamorous: get conversion events flowing through the Conversions API, which lets a website custom audience be built without additional data uploads, and watch Event Match Quality over its rolling 48-hour window to confirm the events are landing on people rather than into a void. Prioritise Email and Click ID, the two parameters Meta ranks High.",[17,394,395,396,400],{},"If you are still building your audience architecture from scratch rather than repairing it, our foundational guide to ",[144,397,399],{"href":398},"\u002Fblog\u002Ffacebook-custom-audiences","Facebook custom audiences"," covers the source types and how each one fills.",[17,402,403],{},"The through-line of all of this is worth stating once. Meta publishes an unusual amount about how these audiences behave, and almost nothing about the thresholds marketers most want. The gap gets filled with folklore, and the folklore sends people re-uploading lists that were never the problem. Read the states Meta shows, read the retention setting on the audience in front of you, and where Meta genuinely has not said, accept that it has not said. That is a faster route to a live campaign than a number someone made up in 2019.",{"title":405,"searchDepth":406,"depth":406,"links":407},"",2,[408,409,410,414,415,416,417,418,419,420,421],{"id":14,"depth":406,"text":15},{"id":31,"depth":406,"text":32},{"id":65,"depth":406,"text":66,"children":411},[412],{"id":94,"depth":413,"text":95},3,{"id":126,"depth":406,"text":127},{"id":151,"depth":406,"text":152},{"id":188,"depth":406,"text":189},{"id":214,"depth":406,"text":215},{"id":233,"depth":406,"text":234},{"id":246,"depth":406,"text":247},{"id":267,"depth":406,"text":268},{"id":385,"depth":406,"text":386},null,"neutral","Why a Facebook custom audience will not fill: the mythical 1,000-user minimum, pixel signal, ATT loss, retention expiry, list formatting, and the Populating state.",[],"md",[428,431,434,437,440,443,446,449],{"question":429,"answer":430},"Does a Facebook custom audience need 1,000 people before ads will deliver?","No, and this is the most repeated piece of folklore on this topic. No Meta Business Help Center page and no Meta for Developers page states a 1,000-person delivery minimum for a custom audience. The numbers Meta genuinely documents are different and narrower: at least 100 customers in a customer list file, and at least 100 members in the origin audience behind a lookalike (value-based lookalikes want at least 100 unique conversions, with 200 or more recommended). Meta guards against small audiences without ever naming a threshold: the Marketing API refuses removals that would shrink an audience too far, and error 200, subcode 1870047 reads 'Audience Size too Low: You cannot remove users from this audience because it will result in a low audience size and may result in under-delivery or non-delivery of your ads.' Note the scope and the hedge. Meta is blocking an operation and saying 'may', so it names the risk while refusing to name the number. Diagnose against the states Meta shows you (Populating, Ready, Outdated, Unavailable) rather than chasing a number Meta never wrote down.",{"question":432,"answer":433},"Why does my custom audience show Unavailable or a blank size when the status says Ready?","Because size and status are different fields answering different questions, and Meta withholds the size for privacy reasons more often than most advertisers realise. Estimated audience size in the Audiences table can display Unavailable or Populating even while the audience's status column reads Ready. An audience in that state is not broken and is not empty. The correct first move is to read the status column, not the size column, and then check the size inside ad set creation in Ads Manager, where Meta says it will show. If status is Ready, build the ad set and look at the estimate there before you re-upload anything or start rebuilding rules.",{"question":435,"answer":436},"How long should a custom audience take to populate?","Meta refuses to promise a single number, and you should be suspicious of any guide that does. For a customer list, hashing and matching after upload takes a few minutes depending on list size, and the audience moves from Populating to Ready. For changes made through the Marketing API, Meta's developer docs say changes usually take up to 24 hours, and that the processing time grows with the number of records removed and the number of custom audiences in the account. Note the scope: that 24-hour statement is about API changes, not a guaranteed user-interface populating time. For a website custom audience, Meta says only that how soon you can use it depends on your website traffic and when you placed your Meta Pixel. A brand-new or newly linked ad account is a separate case again: it may wait a few weeks before it can create or share a customer list custom audience at all, which reads exactly like an audience that never populates.",{"question":438,"answer":439},"Why is my website custom audience so much smaller than my pixel event count?","Because pixel fires and audience members are different units, and the gap is bigger than it looks. One visitor can fire many events but is counted once. Visitors have to be Meta technologies users to be counted at all, and accounts that opted out of online behavioral advertising are excluded. Meta's own worked example on its troubleshooting page turns 20,000 reported visitors averaging seven pages each into roughly 2,857 unique visitors in the audience. That is a 7x compression before you subtract non-users and opt-outs. So an audience that looks catastrophically small next to your analytics traffic can be behaving exactly as documented. Compare it against unique users in the retention window, not against pageviews or event totals.",{"question":441,"answer":442},"Did Apple's ATT prompt shrink my retargeting audience?","Meta confirms the direction and nobody credibly publishes the size of the effect. Meta's own help page on creating a website custom audience states plainly that the audience's size may decrease because it may not include events from some iOS 14 users, and that using it as a lookalike source does not affect the lookalike's size. That is the primary, web-side fact. For scale, the only figure worth quoting is directional and from a different domain: AppsFlyer reported in April 2025 that 50% of users globally consent to tracking, four years after the framework launched. Treat that as vendor measurement of mobile app ATT, not a measurement of your website pixel pool, and do not let anyone convert it into a claim that half your web audience vanished. No verifiable figure exists for web retargeting shrinkage.",{"question":444,"answer":445},"What formatting mistakes cause a customer list to match badly?","The country code is the classic one. Meta matches on a global scale, so every phone number needs its country code even when every number on the list is from the same country, and country belongs in its own column as an ISO two-letter code, even when every row is from the same country. A list exported from a local checkout very often stores numbers in a local format with no international prefix, and those rows match poorly or not at all. Full names must be split into separate first name and last name columns rather than sitting in one field. The file itself must be CSV or TXT, must include at least one main identifier, and must contain at least 100 customers. Fix the columns before you blame the match rate, and be sceptical of any published match-rate benchmark, because Meta does not publish one.",{"question":447,"answer":448},"Can I build a retargeting audience without browser pixel data?","Yes, and this is the underused fix. Meta's Custom Audiences developer guide states that if conversion events are shared through the Conversions API, a website custom audience can be built without additional data uploads. Server-side events are not blocked by browser restrictions in the same way, so a pool that has thinned on the browser side can be rebuilt from server events. Your readout for whether those events are actually matching to people is Event Match Quality, scored 0 to 10 for website events sent through the Conversions API and calculated from the last 48 hours of data. Meta ranks Email and Click ID as High priority parameters, and lists Phone number, Country, Birthdate, External ID and Browser ID among the Medium priority ones. Send more of the High priority parameters and the score, and the audience, should respond.",{"question":450,"answer":451},"Can Meta block a custom audience from being used at all?","Yes, and a blocked audience can look identical to an empty one if you are only watching the size column. Since 2 September 2025 Meta proactively flags custom and lookalike audiences that suggest information not permitted under its terms, for example specific health conditions such as arthritis or diabetes, or financial status such as credit score or high income. A flagged audience cannot be used for new campaigns, and through the Marketing API it returns operation_status 471. A flagged seed also poisons any lookalike built on top of it. The trigger is often nothing more than what the audience was named or how the rule was described, so a supplement or clinic brand with an audience called after a condition will hit this and may never work out why. There is a review-request path in Ads Manager and Audience Manager if you believe the flag is wrong.","\u002Fimages\u002Fblog\u002Ffacebook-custom-audience-not-populating-hero.webp","Your audience says 0, or Unavailable, or it has been Populating for a day and a half, and the campaign is sitting there unpublished. Before you re-upload the list again, work through what Meta actually documents about how these audiences fill, expire, and get withheld from you. Half the time the audience is fine and the reading is wrong.",{"reviewedAt":455},"2026-07-15",true,"\u002Fblog\u002Ffacebook-custom-audience-not-populating","2027-09-15",{"title":5,"description":424},[461,465,468,471,474,477,480,483,486,489,492,495,498,501],{"label":462,"url":463,"year":464},"Meta Business Help Center - Troubleshoot website custom audience size","https:\u002F\u002Fwww.facebook.com\u002Fbusiness\u002Fhelp\u002F1523083297982009","2026",{"label":466,"url":467,"year":464},"Meta Business Help Center - Options to Create a Website Custom Audience (retention windows, rule limits)","https:\u002F\u002Fwww.facebook.com\u002Fbusiness\u002Fhelp\u002F2539962959620307",{"label":469,"url":470,"year":464},"Meta Business Help Center - Create a Customer List Custom Audience (Populating, Ready, Outdated)","https:\u002F\u002Fwww.facebook.com\u002Fbusiness\u002Fhelp\u002F170456843145568",{"label":472,"url":473,"year":464},"Meta Business Help Center - Customer list formatting guidelines for custom audiences","https:\u002F\u002Fwww.facebook.com\u002Fbusiness\u002Fhelp\u002F2082575038703844",{"label":475,"url":476,"year":464},"Meta Business Help Center - Create a website custom audience (iOS 14 note)","https:\u002F\u002Fwww.facebook.com\u002Fbusiness\u002Fhelp\u002F1474662202748341",{"label":478,"url":479,"year":464},"Meta Business Help Center - Create an Instagram Account Custom Audience (365-day engagement retention)","https:\u002F\u002Fwww.facebook.com\u002Fbusiness\u002Fhelp\u002F214981095688584",{"label":481,"url":482,"year":464},"Meta Business Help Center - Create a video engagement custom audience (post views vs campaign views)","https:\u002F\u002Fwww.facebook.com\u002Fbusiness\u002Fhelp\u002F1099865760056389",{"label":484,"url":485,"year":464},"Meta Business Help Center - About Custom Audiences (500 per ad account)","https:\u002F\u002Fwww.facebook.com\u002Fbusiness\u002Fhelp\u002F744354708981227",{"label":487,"url":488,"year":464},"Meta Business Help Center - Understand restrictions on certain custom audiences","https:\u002F\u002Fwww.facebook.com\u002Fbusiness\u002Fhelp\u002F1055828013359808",{"label":490,"url":491,"year":464},"Meta Business Help Center - About Event Match Quality","https:\u002F\u002Fwww.facebook.com\u002Fbusiness\u002Fhelp\u002F765081237991954",{"label":493,"url":494,"year":464},"Meta for Developers - Marketing API, Custom Audiences guide","https:\u002F\u002Fdevelopers.facebook.com\u002Fdocs\u002Fmarketing-api\u002Faudiences\u002Fguides\u002Fcustom-audiences\u002F",{"label":496,"url":497,"year":464},"Meta for Developers - Marketing API, Lookalike Audiences guide (100-member seed minimum)","https:\u002F\u002Fdevelopers.facebook.com\u002Fdocs\u002Fmarketing-api\u002Faudiences\u002Fguides\u002Flookalike-audiences\u002F",{"label":499,"url":500,"year":464},"Meta for Developers - Marketing API error reference (subcode 1870047, Audience Size too Low)","https:\u002F\u002Fdevelopers.facebook.com\u002Fdocs\u002Fmarketing-api\u002Ferror-reference\u002F",{"label":502,"url":503,"year":504},"AppsFlyer - Market adaptation to a privacy-first ecosystem, four years after ATT (press release, directional app data)","https:\u002F\u002Fwww.appsflyer.com\u002Fcompany\u002Fnewsroom\u002Fpr\u002Fpost-att-growth\u002F","2025",[506,510,513,516,519,522,525],{"label":507,"value":508,"source":509},"Minimum customers in a customer list file","100","Meta Business Help Center, 2026",{"label":511,"value":508,"source":512},"Minimum members in a lookalike origin audience","Meta for Developers, 2026",{"label":514,"value":515,"source":509},"Website custom audience retention ceiling","180 days",{"label":517,"value":518,"source":509},"Retention ceiling for purchase-event rules","2 years",{"label":520,"value":521,"source":509},"Compression from reported visits to audience members (Meta's worked example)","7x",{"label":523,"value":524,"source":509},"Customer list flips to Outdated after","30 days without an update",{"label":526,"value":527,"source":528},"Global mobile ATT consent to tracking (directional, app data)","50%","AppsFlyer, 2025","blog\u002Ffacebook-custom-audience-not-populating","IH5q8hjYoRmO8nHxW8Rx7w3jhpZ0rUGEMx1azPrB9o8",1786093701368]