Thunderbird will not accept "username or password" confirmed valid in Gmail
I have a dozen gmail accounts working fine with TB 78.11.0 (64-bit) Win10. I am unable to add one account. Gmail security says specifically that TB has access to this account. Less secure App setting is enabled. 2 factor authorization is disabled. TB is using standard OAuth2 verification. Cookies are enabled. I have had this problem with different gmail accounts in the past. If I delete TB and reinstall, this account will probably be accepted, but then there is a chance that one or two other accounts will have this hangup when I try to add them to the reinstalled TB. I have checked that there is no stored password for this account in TB. I have deleted the history. I have restarted TB and the entire computer many times. Only the crapshoot of deleting TB and reinstalling seems to help. Any ideas?..........then, just as I was about to launch this inquiry, I tried entering the same email address WITHOUT CAPS. It worked. Many of my other TB accounts are entered WITH CAPS, WITHOUT PROBLEMS. Why is this an issue for TB? I thought email addresses were not case sensitive..... ??