Step by step
Open Users & Access as owner
Find the person under members.
Check Suspend / Remove
If they were Suspended, use Reactivate. If Remove access was used, they need a new invite.
Check login role
A tighter role (for example read_only) hides owner settings. Change role if appropriate.
Still failing?
Follow Staff can’t log in for invite/email/OTP basics, then Account security for 2FA.