I tried several 2-factor authenticators and finally got one to work. On my phone I have Duo and it is not giving a valid code. I got a message " a verification code was sent to xxx@xxx.com but it never arrived. I get new login notifications or email changes immediately. I tried 2 email addresses in case there was a problem with one. They both behave the same way. I always get a the message on the sign on page that a code was sent to xxx@xxx.com. Is it picking up the period at the end of the sentence? Not likely, I'm sure. For me the best solution is to NEVER log out again but if I buy a new computer I'm going to have trouble again.