We're getting reports that certain users are experiencing issues with a list of pages they're working with: some of the pages are not listed in Configure Tab. Most users who have been experiencing this have their pages owned by Business Manager.
The reason is a bug on Facebook's side, you can follow it here - https://developers.facebook.com/support/bugs/686883248416658
Facebook team is actively working on fixing the issue. We're continuing to monitor the situation - further updates will be posted in this incident.