If any of your audiences that were published to Facebook (your Facebook ad account or client Facebook ad account) and is not accessible in the Audiences section of the Facebook Ad Account Manager, you will see the audience grayed out with a padlock symbol. If you have "Partnership Access" to that Ad Account, you can log in there and hover your mouse over the audience - it will display an error similar to the message displayed below:
{"error":{"message":"(#2654) Customer List Audiences Are Not Available: Ad accounts owned by businesses new to Facebook Products can create customer file Custom Audiences after several weeks of following our policies.”
This can happen for a couple of reasons:
The Facebook Business Manager / Ad account is too new. Facebook needs to approve the Business Manager or Ad Account, and then you will be able to access your custom audience. Contact Facebook for help getting your Business Manager or Ad Account approved.
Your audience or campaign does not meet the Facebook Advertising Policy guidelines. Make sure to review the "special ad categories" as well. If you believe the content block was without merit, you will need to contact Facebook.