I have several Google Apps accounts, and two of them I've added without a problem. I'm trying to add a third, and after I enter my email address, password and two-factor token from Authy, it tells me "Sorry, there seems to be a problem. Please try again." I've tried this over several days.
I did use to have this account on my phone, but it seems I can't add it back after a factory reset to revert from an Android N preview.
I can sign into this account just fine from a desktop browser or from the Android browser in incognito mode.