Hi, we'd request you follow the below steps:
1. Check your phone for latest software version.
2. Go to Camera settings Clear cache & storage of Camera App after backing up & disable/re-enable camera App
3. Try the same under safe mode:
Hold the power button for 5 seconds => When the screen flashes with option => Press & hold power option => You will get an option to restart in safe mode
4. If still you face the issue factory reset your phone after taking a full backup: https://www.asus.com/support/FAQ/1006346/