UPDATE: according to our latest info, Facebook is planning to remove Custom Audience sizes from all their audiences. Is not yet clear if this will be limited to audiences where personal data has been used, like those created by importing a customer file or using data from the Facebook pixel with Advanced Matching. The reason seems to be that this feature was abused by some advertisers, making it possible to gain access to information that was not supposed to be publicly available. So we are not talking about a bug anymore, but a new approach.
UPDATE 2: This Marketing Land article has interesting details about the cause of the problem. A research team from Northeastern University found an exploit in which it could infer attributes of an individual included in an uploaded Custom Audience list of emails, addresses or other personally identifiable information (PII) using the estimated reach reporting available in the advertising interface:
“It turns out there is a rounding threshold in those estimates. Once that’s identified, an advertiser could potentially upload a list of emails right on the rounding threshold, for example, and then add one email (or “victim”) to the list. If the reach estimates change when a targeting attribute is selected, the advertiser can infer that person has that attribute. And vice versa, if it doesn’t change, then it can be inferred the person does not have that attribute.”
The research team alerted Facebook about the issue and was rewarded through the bug bounty program.
If you used your Facebook Ads account recently, you might have noticed some very strange things. Don’t worry, there is nothing wrong with your ads, or with your pixel, it’s just a technical problem that Facebook is having.
Apparently, it started on December 22, and Facebook is still looking for a proper fix when this article has been published.
We’ve been in contact with Facebook Support, and that’s what we know so far.
Estimate for your audiences are unavailable
When you create an ad targeting your existing Custom Audiences, you might see a message saying that estimates are not available.
Custom Audiences Size Not Available or -1
It possible that you won’t see the size of the audience anymore, regardless the fact that they are ready.
When this happens
This can affect several types of audiences:
- Website and mobile app Custom Audiences if using advanced matching
- Custom Audiences from a customer file
- Offline conversions Custom Audiences
Website or mobile app Custom Audiences that do not include customer data and engagement Custom Audiences are unaffected by this update.
What happens with your ads?
Everything will work fine, and ads delivery and reporting will remain unaffected by this change.
You will still be able to create Custom Audiences, as well as ads using any type of Custom Audiences on Facebook. It’s only the reach estimate that’s missing.
What if you’re a PixelYourSite user?
If you use PixelYourSite Pro, chances are that you’ll be affected by this bug. We do send Advanced Matching data everytime we can (for logged in users, or for the Purchase event, after a transaction), so it’s possible that your Custom Audiences will display size “Not available” for now.
Nothing to worry though, since everything else works fine.
When will be fixed?
According to Facebook, they are currently investigating solutions to restore these reach estimates in their interfaces.