The appears repeatedly in the log:
[2017.07.12-14.57.06:022][ 4]LogHMD: Initializing OVRPlugin session [2017.07.12-14.57.06:652][ 4]LogHMD: Setting user focus to game viewport since session status is visible... [2017.07.12-14.57.06:659][ 5]LogRenderer: Reallocating scene render targets to support 2080x1024 Format 2 NumSamples 4 (Frame:10). [2017.07.12-14.57.06:822][ 6]LogRenderer: Reallocating scene render targets to support 2560x1440 Format 2 NumSamples 4 (Frame:12).
When packaging the same map/project with GearVR disabled in Android settings, this app didn't have the issue
Other devices haven't been tested yet, but this didn't occur in 4.16
I was able to repro this with the HMD and without (dev mode)
1. Create new BP or Code project for mobile and load the editor
2. Disable HDR
3. Set up project for GearVR according to UE4 documentation
4. Save the blank map and make it package default
5. File > Package > Android ETC2
6. Install to phone and launch app
RESULT: The level loads and the display flickers off and on slowly
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-47148 in the post.