Fix Facebook Custom Audiences Sync Errors in Segment – Twilio Support

Issue

When using Twilio Segment, you may find that your Reverse ETL sync to Facebook Custom Audiences is not populating existing audience lists, or you are unable to create a new audience or select an existing one while configuring a mapping. Additionally, you may notice that the resulting audience size in Facebook is significantly smaller than the number of records extracted.

Product

Twilio Segment

Environment

Segment Console

Cause

This issue is typically caused by either an authentication error or a low match rate due to insufficient user identifiers.

If the audience is not populating or cannot be selected, the Facebook user who authenticated with Segment likely lacks the required permissions for the configured Advertiser Account ID. If the audience size is smaller than expected, it means Facebook's internal matching logic could not find enough user profiles based on the limited identifiers sent from your data warehouse. For example, sending only a B2B work email might fail to match a user if their Facebook account is registered under a personal email address.

Resolution

To resolve authentication and permission issues:

Navigate to your Facebook Custom Audiences destination settings in the Segment Console.
Verify that you have authenticated with the correct Facebook account.
Ensure that the authenticated Facebook user has at least an Advertiser or Admin role on the target Ad Account.
Confirm that the user has access to the specific Advertiser Account ID configured in Segment.

To resolve low match rates and increase audience sizes:

Open your Reverse ETL model mapping for Facebook Custom Audiences.
Map as many user identifiers as you have available in your source model (such as email, phone number, mobile advertising IDs, first name, last name, city, state, etc.) to the destination fields.
Save the mapping and allow the next sync to run. Providing more data points greatly increases the likelihood of a successful match on Facebook's end.

Additional Information

Facebook requires all Personally Identifiable Information (PII) to be SHA256 hashed before it is sent to their API. You do not need to manually hash this data before syncing; to improve match rates, Segment automatically handles the formatting, normalization (e.g., stripping whitespace and converting to lowercase), and SHA256 hashing of unhashed PII like emails, phone numbers, names, and locations.