GearVR trackpad quadrant buttons not detected in TM-MotionControllers

Using the TM-MotionControllers map as a test for GearVR, the 4 buttons in the trackpad quadrants of the bluetooth controller don't register via the blueprint.

This issue did not occur on Vive at the same CL.

SETUP: Pair a GearVR motion controller with a VR ready phone

1. Create new Code project for mobile and load the editor
2. Disable HDR
3. Set up project for GearVR according to UE4 documentation
4. Exit the project and load QAGame at the same CL
5. Migrate the TM-MotionControllers map and references to the new project
6. Back in the new project, package this map
(File > Package > Android ETC2)
6. Install to phone and launch app
7. Press all the trackpad buttons

RESULT: Trackpad x,y input is detected, but not the buttons