Several users have found that after upgrading to iOS 11.1, they are experiencing a weird issue while they are on a call or using Facetime. While on the call, if you open other apps, the screen for the new app opens up partially (only half of the screen) and does not respond to any taps. This happens on iPhone 6 models as well as some of the new 7 and 8 iPhone models.
It appears that this is probably a bug and will be fixed in a later upgrade.
How-To Fix The Screen Not Responding Issue
If you have already restarted your device and or restored it and are still experiencing this issue, you may want to check out the Reduce Motion settings and switch it off.
Tap on Settings > General > Accessibility > Reduce Motion. Turn this to OFF.
This quick workaround should take care of this black screen issue on your iPhone when you are using it on a call or facetime. The problem doesn’t seem to show up when you are using other third party communication apps such as Skype.
What You Should Know About Reduce Motion
Reduce Motion can even make your iPhone or iPad feel faster, especially if you happen to have an older device in hand.
Please note that the Reduce Motion feature is closely tied to certain iMessage effects functionality. If you are not a fan of the iMessage animations in messages, you should consider switching off the ‘Auto Play Message Effects”.
iOS 11.1 is definitely a worthwhile update if you have not yet updated. The battery is holding up more compared to the prior version except when you are using YouTube app. There are other fixes and a security vulnerability that was fixed in this latest iOS 11.1 upgrade. If you are not sure, you can check out the feature guide for iOS 11.1
This issue around black screen or partial screen, while on the phone app or Facetime app is not as widespread and is happening only to some devices.
We hope that this quick workaround fixed your issue for now and are also hoping that this will be fixed when iOS 11.2 is released in the near future.