Kindly head to the Support tab of the Samsung Members app and conduct all Phone diagnostics related to the camera(s). Do they all pass? Try this really quick. Settings>Apps>Camera>Storage>Clear data. This will essentially reset the camera and you will lose all settings. If this still doesn't work... with the phone powered off, press + hold power and volume up buttons until the Samsung logo disappears. Using volume keys, highlight Wipe cache partition, and then power to select and confirm. Returning to the previous menu, use volume keys to navigate to Repair apps, and then power again to select and confirm if necessary. This will reindex all apps on your phone.