Steps to reproduce:

1) Download attached project 'S6EdgeBug.zip' and open in Unity
2) Create .osig file for testing device
3) Make sure in Player settings Virtual Reality Supported is enabled and SDK is Oculus
4) Enable Developer Mode in Gear VR Service on a device
5) Build and run 'ReproScene' on a device
6) Slightly rotate device and click on Volume buttons(to increase or reduce sound volume)

Note: There will be image distortions around the sound pop up (see attached image)
Note: Works fine with Cardboard SDK

Reproduced with:
5.4.4p1, 5.5.0p4, 5.6.0b4

DUT:
Reproduced with:
Samsung Galaxy S 6Edge[SM-G925F], Exynos 7 Octa, OS version 6.0.1(reproduced only on this device)

Not reproduced with:
Samsung Galaxy S7 Edge[SM-G935F], Exynos 8 Octa, OS version 6.0.1
Samsung Galaxy S7[SM-G930V], Qualcomm Snapdragon 820, OS version 6.0.1