Please perform the below mentioned step to resolve the issue:
1) The device may not recognize fingerprints that are affected by wrinkles, small or thin fingers.
2) To improve recognition performance, register fingerprints of the hand used most often to perform tasks on the device.
3) Ensure that your fingers are not wet, they should be clean and dry.
For further assistance, register your concern in Samsung Members Application (Open Samsung Members Application > click on “+“icon > send feedback > error report/ask questions).
