Hi there, kindly follow the below steps:
1 . Update your device to the latest firmware version if not already, on Android 9 which is Version WW-16.2017.2007.084
2 . Clear system cache.
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/1006346/5. Last option would be to visit the service center to have
a check. Locate here:
https://www.asus.com/in/support/Service-Center/India