Having the TD Bank app set up to not use biometrics to log in does add to the mystery. And the actual source of this instability is still in question. Since this problem may or may not be tied directly to the lock screen, another thing to try is completely reset your lock screen options. Delete your lock screen settings or set them to their defaults, restart your phone, and then restore your lock screen options accordingly. Perhaps that update from a couple of months ago created some kind of corruption in a lock screen config file that only gets used in specific situations (i.e. some background process used by the TD Bank app), and that triggers this weird instability issue. But this is all just random guesses for the most part.
This is a definite, last resort suggestion but given the fingerprint reader sensor has apparently been messed up since you've had this phone, you might want to consider do a Factory Reset. But be sure you have safely backed up all your personal data and you have a record of your user name/passwords for the apps you use to access your different online services. A Factory Reset wipes your entire user account, and doing a complete, full restore can be a really arduous project. (Double check your backup data too, a lot of people make bad assumptions and lose precious files -- i.e. do not rely upon the Google backup and restore option in your Settings menu as a comprehensive backup utility, it only apples to Google apps and services data.)
