Chrome Version: 72.0.3595.0
OS: Win 10
Graphics Card: Radeon 580 4GB
VR Headset: Windows Mixed Reality

What steps will reproduce the problem?
enable WebXR Device API, WebXR gamepad, and openvr flags in Chrome.
(1) Open Windows Mixed Reality app, and put on headset so that the WMR home VR app starts. 
(2) Open Chrome to https://immersive-web.github.io/webxr-samples/positional-audio.html and click Enter VR.

What is the expected result? The WebXR presentation is started on the headset. 

What happens instead? 
- The WMR home app environment is still displayed, yet the controllers become inaccurate, and the floor height changes. It becomes unusable.
- WebXR shows that it is in VR mode and the desktop display window responds to head movement.