Input events stop getting handled when being touched/pressed from multiple devices

When our app is launched, while tapping repeatedly on the screen with one hid-multitouch device, if I touch the screen with another different hid-multitouch device, the app will behave in a weird/inconsistent manner.

Some things I see (inconsistently) when it happens:

1. A traditional USB mouse will work, but when clicking, the controls will only react as if a button-press is happening.
2. USB mouse not working at all.
3. Touch screen clicking random parts of the screen (even some parts which I believe are hidden).
4. QEvent::TouchEnd doesn't appear to be raised (I attached an event listener to verify this).

I initially discovered this on an embedded Linux distro (intel i3 x64). I can also reproduce this locally on Ubuntu 18.10 with the latest v12 branch.

When running on Ubuntu, when the issue happens, it seems to "kick back into gear" when switching focus to another window and then back again. Unfortunately, this isn't possible on our embedded device, so I need to search for a solution.