Please perform the following steps to resolve the issue:
1- If any screen guard/tampered glass/protection film is available then first disable the fingerprint settings and then remove the screen guard.
2- Once screen guard is removed now register the fingerprint again and check the issue.
3- If problem does not get resolved, run the device in Safe mode and reconfigure the fingerprint.
4- If issue still persists, create data backup and reset the device.
5- Check for the latest device O/S (Settings > Software Update > Download updates manually).
For further assistance, register your concern in Samsung members application (Open Samsung members app >> click on “+“icon > send feedback >> error report / ask question).
Team Samsung Members