Certainly you may use hydro gel protector For your device Hydrogel are best for in display finger print scanner Or You may register same finger 2-3 times And clean your screen before unlocking.
Smudges on screen may effect finger print reader And if you keep brightness somewhat high Then also you will able to unlock your device easily
Please perform the below mentioned steps to resolve the issue:
* To improve recognition performance, register fingerprints of the hand used most often to perform tasks on the device.
For further assistance, register your concern in Samsung Members Application (Open Samsung Members Application > Get help > Send Feedback > Error report/Ask questions).
