Unified Inbox out of sync

Android 10 Oct !
My Unified Inbox is ill.

  1. The first several are older ones.They are not (AFAIK) starred
  2. The box does not show all the mail.
  3. The first entries are out of sync; I touch the top entry, I get the second email popping up.

I assume I’ve misconfigured something but don’t know what.