What causes iOS 11 iPad recent apps dock icon to be grayed out?

Question

I have an app that I have "inherited" to maintain.

Since the iOS 11 update, on two separate iPads (iPad Air and iPad 5th gen), I have a problem. Both devices are running iOS 11.0.2.

When the app is installed and launched for the first time, the app icon shows up in the "Recent apps" section of the dock, but the icon is grayed out and cannot be tapped (it can be dragged, but long-pressing does nothing). For any subsequent app launches the dock icon remains unchanged, unless any process occurs that causes the app icon to go away from the "Recent apps" section (opening a few other apps or dragging the icon to the left side of the dock) then the icon is no longer grayed out and it becomes tappable. It looks the same as if the icon has been tapped, but it is permanently in that pressed state (it does not trigger a long press event).

The problem occurs when the app is installed from the App Store, XCode (Debug session) or Crashlytics. It re-occurs after uninstalling the app and re-installing, even if the dock icon was "fixed" during the previous installation.

The home screen app icon is fine (not gray and can be tapped).

What could be the cause of the problem? Or is it an iOS 11 bug?

Edit 1: This problem does not occur in the iOS11.0 simulator.

Edit 2: Updating the iPad (5th gen) to iOS 11.0.3 did not fix the issue.

Edit 3: Rebooting the device (either between uninstall and reinstall, or while the icon is gray) fixes the icon. This leads me to believe that there are possibly some files left over or something is still happening after deleting/uninstalling the app and this cache or whatever is only cleared on reboot. Waiting 10 minutes after deleting the app has no effect.

Edit 4: As pointed out by Marko in the comments, "The greyed out icon does work to switch back to the app when dragging it to the screen, but not when tapping on it."

This seems to be related to xCode, and possibly having an orphaned app icon. I discovered that if I install-uninstall-reinstall the App Store version of the app it does not have this issue. This issue only occurs when installing (debugging) from xCode or Crashlytics/Testflight. If the xCode version was installed-uninstalled then the App Store version is also affected.

Edit 5: I noticed that if the icon is not gray and I delete the (debug version of the) app, just before the icon disappears from the recent apps dock it turns gray and then is removed.

Update: I have replicated the bug with the App Store version of my app, but I have also been able to replicate the error with the Google Play Music app. As such I think that this is not a problem only with my app (and a few other devs), but it appears to be an iOS 11 bug. I am going to answer my own question that this is an iOS 11 bug.

Answer 1

After some more testing, I have come to the conclusion that this is an iOS11 bug. I was able to replicate the bug with my own app and another app that is live on the App Store (Google Play Music).

This appears to happen when uninstalling an app that is present in the "Recent Apps" section of the dock. Upon reinstallation and opening the app, the icon is grey.