Hi there! Sorry for the delayed response. We could recommend to try turning the phone off and on and test again. You may also try doing a factory reset and test the fingerprint from the start again. Please try this and keep us updated with the results.
Thanks. Please make sure the screen is wipe and start the process.
Hello there Saphire978. Unfortunately, this sound like a device issue more than a setting set up. Please contact LG Support at 1-800-793-8896 for assistance.