Our group has never enabled or required 2FA. One of my users all of a sudden can't log in because he's now required to provide a 2FA code. He's never set this up (and neither did I as the Admin, we would need to upgrade to have access to this feature). 

Any thoughts as to why this is happening all of a sudden? Was there a breach somewhere? He changed his password to try and get around this, thinking it was a glitch, and I see that activity in the console, but nothing else.

Help?