Passthrough randomly disables during runtime

UE 5.5.4.  Meta XR plugin v78.

I have an apk that I sideload onto several headsets.

The app works fine while connected to my laptop for development.  Never an issue.

The packaged apk works fine on the headsets during testing.  Seems solid.

But then I'll launch the app and hand out 10+ headsets to the customers, and they walk around for a while, eventually some of the headsets lose passthrough.

The app is still running and tracking.  You can see the virtual objects, but they are on the field of black.  You can't see and of the surroundings.

Double-tapping the side of the headset simply pauses the app and takes me to the menu.  I can't get passthrough working again once this happens.

I added blueprint code that every 10 seconds checks if the passthrough object is null and, if so, initialize another passthrough, but that didn't help.

I've fired up 10 headsets let them run and walked around the room holding several of them, grabbing them all over the headsets (in case the customers are pressing some button), but I can't get the passthrough to stop working.  Hence why I don't have a log file to attach.

I'm at a loss what could be happening and how to recreate the issue.

Any help or suggestions would be appreciated.