I may have found a bug with the AR motion tracking. It happens whenever I tilt my phone (Google Pixel 2) almost horizontal (so it is "looking" down at the ground), and then move then phone sideways left or right in a linear motion... Whenever I do this, the AR system appears to pause... Camera position doesn't get updated, no ARplanes are detected... after a couple of seconds it all starts working again. Also, when I close the AR app, I get "Deactivating AR" appear on the screen... Is AppGameKit doing that, or is it ARCore? Either way, it's annoying. p.s. I've only been testing this in broadcast, so don't know if this also happens on installed apk.
[EDIT]: I have also noticed the same "AR Pause" when interacting with virtual buttons (but not every time)... i.e. press a virtual button and the AR will sometimes freeze for a couple of seconds.