Why you might not be able to see all of your custom audiences as a source for your lookalike audiences
When creating a lookalike audience, you'll need to select a custom audience as a source.
In the lookalike audience creator, once you've selected the ad account you want to create your lookalike in, you'll be presented with a list of available custom audiences in the source dropdown.
Custom audience missing from your sources?
If you're expecting to see a custom audience in the list of sources, this might be why:
Your custom audience isn't eligible as a source
Your custom audience must contain at least 100 people from a single country in order for it to be eligible as a source.
Your audience is in a different ad account
Make sure you've got the correct ad account selected - and that you have the correct access. You can check this here.
You need to refresh the connection between TrustAds and your Facebook account
If your custom audience was recently created, you might need to refresh your connection to TrustAds.
To refresh your connection, log out of your TrustAds account, then log back in using the Login with Facebook button.
N.B. Make sure you're logged into the Facebook account linked to your chosen ad account!