Sounds like a bug. I reported it to Oculus (since it’s mostly SDK issue I think): Solved: [Gear VR] How to shut down app on exit to the Stor... - Meta Community Forums - 381582 but I haven’t done logcat stuff before, so I am not sure what exactly to do in order to provide what they are asking for.
Are you familiar with all that debugging stuff for Gear VR and UE4 ? If so, do you think you can pitch into that report and provide logcat log to Oculus ?