You should make sure you do not have a GateHub account added to your 2FA app more then one time, which could happen if you disable 2FA in your GateHub account and re-enable it but not erase the old account from the app. This way you could be entering the code from the wrong account in the app.
Also, make sure the time on your 2FA app is synced correctly (Time Synchronization for your 2FA App).
If the reason is not one of the above, we suggest you perform a hard refresh of our sign-in page and if the issue persists, please contact our support team, choosing the category 2FA-disable.