We have a similar problem.
An admin no longer has any data.
I myself have changed his password in the profile. However, I get the message "You do not have permission to do this" - but it still works.
It fails at 2FA, however. Under the option "Two-Factor Authentication" it says: "Nothing to disable" even though he has definitely activated it. Now he can log in with the password, but then he can't go any further.
Can someone please help us?