Exchange Online No valid Azure app found

Hi everyone,

For about a week now, we have 2 failed mailboxes in the Exchange Online backups that have the failure reason “No valid Azure app found. Please run Check Readiness”. In the same backups we have 346 mailboxes that show no issues.

Only these 2 mailboxes have issues and I cannot find what is causing this. The mailboxes still exist and are no different from other shared mailboxes.

The logs show no different errors for the mailboxes so I am a bit at a loss. I also see the same issue for multiple Exchange applications.
Does anyone have an idea how to resolve this?

Kind regards,
Paul