Attempts at renaming my primary alias are failing.

Here is response I receive when using your tool:
"You can't use your alternate email address as Microsoft account. Please enter a different Microsoft account."

I even, just now, tried re-adding and then removing the email (*** Email address is removed for privacy ***) as an alternate hoping it would fix the problem / clear the system issue on your end.

Please make the Engineering Team aware of the problem, so they may work to fix it.

Kind regards,