Firstly, confirm that your contacts are synced on your device. then , check permissions and, if that fails, set the default Phone app.
Alternatively, you'll uninstall third-party apps that have anything to try to to with calls or clear data from the Phone/Dialer app. you'll also reset app preferences or uninstall updates for the system dialer app.
1. Check permissions for the Phone/Dialer appThe first thing you would like to try to to is to see permissions. generally , the pre-built Phone/Dialer app should have permissions to access Contacts but, only for the sake of troubleshooting, we’ll need you to see this. Of course, if you're employing a third-party dialer app (e.g. Google Phone rather than Samsung Dialer), you’ll got to grant it permissions so as to ascertain names for contacts with incoming calls.
Here’s the way to check permissions for Phone and permit it to access Contacts:
Open Settings.Select Apps & notifications (Apps).Select All apps (App manager or Manage apps on some Android skins).Open Phone or Dialer (the app you employ to form and receive calls).Tap Permissions.Make sure that the app has permission to access Contacts