You should have brought it back as soon as you noticed you were having a problem. I would say to go into the settings menu and go into the fingerprint menu and delete all of your fingerprints. Then add your fingerprints back into the phone remember to add more than one fingerprint you can add the same one multiple times but add more than one, make sure you finish the process . Than try it if it still doesn't work I would bring it back to where you bought it and tell them to fix it or replace it hopefully it's within the one year mark so it's still free
remove current fingerprints and add new ones. also, enable touch sensitivity.
have you checked it in safe mode?
or submit an error report via samsung members app if you think it's a sofware issue.