Should somebody from the USA have their number listed like so:?
1 + area code + number ?
(Edit - I managed to get into my account again using the Authenticator app and I will make sure that I have my phone number listed in the correct format, should I ever need to reset my 2FA in the future.)
Yes. We obviously need to know which country to send the SMS to so including the country code is mandatory.
I assumed the "Only use numbers" referred to the use of any dashes or spaces but does it also mean to leave out the + sign that an international number usually starts with?
Since I was able to log back in again using authenticator app, I was able to change my number, all I did was add a 1 to the beginning of my number. I'm not using any symbols at all in the number.
I did not try to reset my account again after I got back in and changed my number, but I am assuming that that is the correct format to use, without any symbols at all, only numbers.