Is it possible that any background apps could be stealing focus from the game window?
I've noticed that I get graphical glitches / mild stuttering in VR apps if I intentionally alt-tab out of a game window to something else, that always goes away after returning focus to the game app. And occasionally when I launch Elite Dangerous it won't automatically have focus to start with.
It's hard being the voice of reason when you're surrounded by unreasonable people.