Same problem:
https://support.mozilla.org/en-US/questions/1339429#question-reply (archived)
How can I get a suitable 6-digit authentication code to use in browsers on Windows 10?
Codes provided by neither of the authentication app's on my phone (Google and Microsoft) work.
https://support.mozilla.org/en-US/questions/1339429#question-reply (archived)
How can I get a suitable 6-digit authentication code to use in browsers on Windows 10?
Codes provided by neither of the authentication app's on my phone (Google and Microsoft) work.