I am the other guy on Reddit as mentioned in AmazingTechVR's post. I have literally done everything to try and debug this issue. Reinstalled windows, different cables, sent in the Vive Pro 2 and received another unit back and the issue persisted. I also own the Vive, Vive Pro, Oculus Rift, and the Valve Index and none of the other HMDs had this black screen issue. Like AmazingTechVR mentioned, it happens after every cold boot and the black screen lasts for about a second most times, but unfortunately for me quite often the game doesn't come back and I have to close the game, SteamVR, and Vive Console and restart them to get the game to come back. After that initial black screen I have no more issues until the link box has sat powered off for over 10 minutes or so.
My support ticket was finally elevated to higher level support after I had dealt with numerous different support people that kept repeating the same debug steps instead of actually looking at my support history to see what I had been through. This higher level support basically told me that they have seen a 'warm up period' on the extreme mode of the Vive Pro 2 and they sometimes noticed issues until the headset had warmed up. AmazingTechVR mentioned he had the same issue in non-extreme modes and wireless mode so that doesn't seem to be the case.
To me, this HMD is was in the higher price range of current VR products without going to the extreme of the Varjo and Pimax 8k, so I expected a less-buggy experience. But when it is working it is the best HMD I own as far as FOV and picture quality so I will be sticking with it until something better comes along.