Sorry to hear that didn't help. 😕
I'm just a VR user, like you, no VR devs or special VR skills here, I've just been playing in VR already since 2016. 😜
Before I figured out this solution I did find that connecting a monitor to my laptop fixed the problem as well.
Note: Monitor should be ON. Just see if that fixes the issue.
Some thoughts;
1) Since it doesn't work in either cases (Oculus/SteamVR), then I would think something may be preventing your Windows desktop from being "recorded" (mirrored or whatever we would like to call this). I mean; I have never seen it fail in SteamVR ...
Do you happen to be running certain remote desktop software? I read somewhere that these may conflict with Oculus and SteamVR.
Maybe you have some very aggressive AntiVirus protection running? For example, certain applications or profiles protect the user by blocking screen recording.
2) What kind of configuration are you using?
3) I assume you already did this, just in case you didn't: make sure your drivers and Windows are up to date.