I design and develop VR Training apps for the Health sector in the UK and have developed a test version of a new app using the XR Interaction Toolkit using Unity 2020.3.25f1 LTS which I can build and run on both Quest2 and Pico Neo 3 VR headsets without any problem. However after following all of the documented Vive instructions - installing the Vive Wave XR Plug-in with recomended Player settings, the resulting APK installed following the https://business.vive.com/uk/support/focus3/category_howto/installing-apk-on-headset.html instructions, the VR app just shows as a black landscape block and then a portrait transparent block with the Exit/Close X on the bottom. Also happens for a simple scene with just a camera and cube in. I was hoping to run a comparision on the new app across the three headsets and it will be a shame if I can only do with the Quest 2 and Pico Neo 3 headsets for which the VR app runs really well, there are much more detailed and simpler instructions and I experienced no issues.
Here are screengrabs showing the issue and Unity settings.