The main and most common reason why your - Two-Factor Authentication (2FA) - is not working is that your Google Authentication application’s time has not been synced correctly to your cell phone.
To fix this issue, you will need to do the following:
Go to your Google Authentication application
From here, select the menu icon (the three dots)
Select Time correction for codes
Finally, select Sync now
Your 2FA should work now. If you are still experiencing any issues with your 2FA, please contact our Support Agents (here).