Every 6 hours we check the credentials for all the ad accounts. Sometimes the platform API comes back with a denial for a specific credential - with most platforms they don't give a reason, as there is just no credential for us to see.

Sometimes, it'll work when we check it again, other times it's a legitimate issue. The email is sent when we get the initial denial, hence the email was sent.

If a credential is denied access to an account we try the other connections in the app to see if any others do and assign that one instead so actions can keep occurring. This uses the order of the credentials on the connections page - see the image below.

Why don't I see an email listed as the Ad Account user?

With Facebook it is possible to not have an email address associated with the account - it might use a phone number instead - so we display the credential ID as we don't get the phone number.