This build still does not work with Index Controllers.
I just discovered your game, and I love it. This is perfect to use a not so big play space at full potential.
But I can't go too far as I have the same issue. I use the brand new Valve Index controllers, and grabbing does not work. I tried many configurations without success.
I can see a lot of VR : MISSING HAND POSE 0 and VR : MISSING HAND POSE 1 in the log file.
Let me know if you need more.
Keep good work !