Don’t know if anyone will ever find this but I’m compelled to document it, since it cost me a solid half-hour+.
From the Template screen when you first open Word or Excel (or other?), if you click Sign In and the dialog box opens and there’s a different email pre-populated (because your spouse also uses it, or whatever)… and you use the same email provider (because you both use gmail or outlook.com or whatever)… WIPE OUT THE WHOLE FORM and type in your email address.
firstname.lastname@example.org, was replacing ONLY the
999 in the prepopulated email address
email@example.com, and couldn’t log in.
Web searches gave only the obvious advice (restart, reinstall, burn your house down and walk into the ocean). So I reinstalled 9 gigs of Office 365… and it kept happening. (Deleting and reinstalling didn’t wipe out whatever little .plist or whatever had memorized the
Brain flash: Do I delete the whole email address in the window? Is it that dumb? I mean… that’s the kind of mistake I’d make, in a React setState screwup.
Blammo, it worked.