Thank you for the information!
I would advise in this case to have another of the tenant Admins check the MFA/authentication policies in case there’s a situation where you might be required to provide some information ( like an MFA prompt), but your account is not enrolled, nor prompted for enrollment. If everything seems well, another Admin could also delete your account and then re-invite you and see if this helped with the issue.
If all else fails, please send a DM ( Direct Message ) to @support with the email address and also the name of the tenant to which you do not have access. We will pick up the conversation from there and continue assisting.
Have a great one!
Gerald