Dear Samsung Member,
Greetings from Samsung Customer Support!
Please perform the below mentioned steps to resolve the issue:
1. Clear camera application data.
Settings >Apps >Camera >Storage >Clear Data
2. To improve recognition performance, re-register your facelock.
For further assistance, register your concern in Samsung Members Application (Open Samsung Members Application > click on “+“icon > send feedback > error report/ask questions).
Thank you for writing to Samsung.
Samsung Customer Support