I forgot to add -- Exscudo initially told me the 2FA problem was with using Firefox browser, which is my default. That, too, wasn't true -- it doesn't work under Chrome either. So I also submitted a screenshot of that email to originate my complaint.

After I forwarded back to Exscudo their own admission they had 2FA issues is when they started getting pithy about blaming me for their impotent software work. Pretty lame.

Ah, well, I hope this helps someone else get their money out...