PARKOURanger

I've encountered problems with fingerprint security. I cannot add or delete fingerprints. The phone shows that I've added/deleted them, but when it comes to using it, it doesn't recognise new fingerprints, and still recognises "deleted" fingerprints. Upon restarting phone, it shows 2/3 fingerprints I have registered, but I can still use 3rd fingerprint to unlock. And a 4th fingerprint I tried to register doesn't work.