Microsoft Store, new Rig, clean Install, no Add Ons, Game, Geforce and HP latest Drivers, recommended Settings.
The moment i switch to VR, it gets black for a second then crashes to WMR desktop.
No ticket yet, just 
.
i7-11700k @ 3.60GHz 32G 3600 | RTX3090 | 2T m.2 | Win10 | 55" 2k HDTV | HP R-G2
Reverb G2 is known to have power issues (though mostly on AMD systems).
Does it work with other games?
Had this, did all fresh installs. You have updated your OpenXR, and ALL your store apps, and your windows 10 updates, and your HP drivers, and then still cross your fingers.
In my case - I think - it was my windows 10 update, after restart it took 15 min of a seemingly dead PC to restart, and I hit the reset button, and it restarts and everything seems ok, nope it was not. Reinstall windows 10 again, update and just drink coffee and wait for the PC to restart, the latest update Version 21H1 (OS Build 19043.1237) takes ages in the shutdown phase.
It is pure luck when it works.
This ctd/ctr happen when they happen because they happen. As long as we got no crash reports to see what crashes everything is speculative.
Get the V2 connection cable from hp, it is free for V1 users and comes within a few days.
Try to keep your system as clean as possible, no excessive OC and then … pray.
If you have the V2 cable:
Also look at this post where crashes with the HP Reverb were reported as fixed: MSFS 2020 Crash in VR - HP Reverb G2 - #338 by Speler596679479
Other are reporting blackouts with a return to VR after a few seconds. I would suggest checking your USB settings in the BIOS in either case just to rule out that it is not set to ‘AUTO’ or ‘GEN4’. The Reverb only works with setting ‘GEN3’ in the BIOS.
I dont have a new V2 cable, as other games run and MSFS used to run (old rig, pre WU 6) without problems. The Reverb now works in MSFS until i confirm my position (space) and it still works afterwards when it switches back to the WMR room, its just that the sim crashes without comment. 
Very strange, now it seem to work.
Forgot to say, Thanks for the help! 
It is funny and I am not 100% shure if it was the reason but I did the Gen3 trick today and have had my first ctd free 80 minutes flight with the 787 for weeks.
Thank you!
Edit: happy too early 
Still having crash to freeze/crash to reboot with the Gen3 trick. So this is not the reason for MY crashes.