WMR native plugin trigger axis not working

We are testing the new Windows Mixed Reality native support and have found that the trigger mapping to a button is working, but the trigger mapping to an axis is not, i.e. the event MotionController(R)TriggerAxis values always returns zero.

1. Create a virtual reality template project
2. Open the level blueprint
3. Log the MotionController(R) TriggerAxis to screen on every tick
4. Launch the VR Preview on WMR
5. Observe the float values being returned while moving the trigger on the controller

Expected: Values ranging between 0.0 and 1.0 are logged
Actual: Only the value 0.0 is logged