I am guessing that you are an On-Premise user, but correct me if I am wrong.

When 2FA codes stop working the most common cause is an incorrect clock somewhere within the connection (Host users computer, the server, etc). Can't say this is always the problem but it's certainly a good place to start.

And when a user gets locked out, that data is stored within the User.xml within the App_Data directory in the ScreenConnect server installation. If you need to reset someone's locked out status, just stop the services on the server, change that user's "IsLockedOut" value to false, and restart the services.