Google Authentication in Internet Accounts

So, since the problem went away in Safe mode but returned when in normal mode, I decided to try removing Kaspersky Internet Security. That fixed it, so either the base software or the extensions in Safari and Chrome were the culprit.

My default browser is Safari. However, I've tried the change to Chrome (failure continued), then change back to Safari.

I am still unable to add a new Google account to Internet Accounts.

However, I was able to fix my Mail issues (at least for now). I shut down then turned back on, went back into Mail and got one account authenticated. Failed on second account. I shut down / turned on again, went back in and got a second account authenticated. However, when I shut down / turned on yet again, I was unable to ever get my last account (with two-factor authentication) going. Since I wasn't using it much anymore, I deleted it.

I worry that with Internet Accounts having some Google issue, this fix won't last long, and still have no idea why I can't add the first account I deleted back as a Google account.

Sadly, as I suspected, the "fix" was brief. I'm back to not receiving mail on the two accounts that I previously authenticated and got some mail through.

Internet Accounts issues pop-ups for me to enter password on the two remaining (and no longer working accounts), but will not open a browser before "failing to authenticate, try again later".

Thanks, but won't work. You are thinking that it is related to mail. It is NOT. Internet Accounts won't let Google work, that is, when I try to add a Google account, it rejects it prior to ever having an account to authenticate. That is why my brief "fix" didn't last - Internet Accounts came along and wanted "Google Password Required", but it never opens the browser.

So, put another way, Internet Accounts won't open a browser, neither Safari nor Chrome, in order to truly try a password for authentication. So, it will never get to the point where I can add enter an 'app specific password' or any other password for that matter.

One more interesting symptom. Finally tried opening in Safe mode. Internet Accounts worked with Google and opened browser window for authentication. So that got Mail going again.

However, the user group shows no additional apps loaded at login, so there isn't anything obvious to try to remove.