I have this same issue with Oculus rift S. Was working 1.5 weeks ago beautifully.
I’ve:
reloaded oculus, steam, msfs2020, nvidia drivers, steam vr, openxr (windows/steam), changed the xr enviornment (oculus, windowsxr and steam), created a new user profile on the system, deleted windows 10 monitor cache.
I’m currently reloading the PC to see if it helps.
It’s strictly a MSFS issue, because I can pop into assetto corsa and use the headset fine, as well as other titles.
Zendesk / MSFS 2020 support replied with the canned response – nothing helped and I’ve yet to receive any additional replies.
It’s not a resource issue: i9-10850k, 64gig ram, rtx3090FE