Locate the phone call app and give contact permission.
Hold down the app icon for 2 seconds, options will pop out. Then click the "i" icon on the top right corner to access the permission options...
Hope it works¿
Kindly make sure of the following points:
1. Enable Call Notification
To enable the notification again, follow these steps: 1] Open Settings and go to Apps & notifications. 2] Here look for the default Phone app, tap on it. 3] After that tap on Notifications and see if the “Show notifications” toggle is on.
2. Delete Duplicated contacts, or contact which save using two names.
If the issue still persist, kindly register your concern in Samsung Members app (Samsung Members app > Get help > Feedback > Error report/ask question).
Note: Please send device log files within 15 minutes of issue occurrence along with the exact issue details.
Kindly make sure that the device is updated to the last software update.
You may try to clear cache the phone app, from the settings > apps > phone app > storage > clear cache.
Also, please note that in such these cases, the caller himself/herself may removed his/her name of being shown while calling, so please check that.
Otherwise, you may reset all the settings, from the device's settings > General > reset > reset all the settings.