Same for me:
After a restart, I could not change resolution anymore, or refresh rate (both set to weird values, making this bug really hard for my eyes). I have an NVIDIA RTX 2080 graphics card with 535.216 driver installed. Maybe unrelated but: This happened after installing Windows in addition to Vanilla OS on my PC.
Gnome Xorg is missing in login. Yet according to system info, I run X11. Furthermore, when I run nvidia-settings, I get "ERROR: The control display is undefined". When running "xrandr --listactivemonitors" I get "Can't open display" Both I run with "host-shell pkexec".
Somehow it cannot recognize the correct display. I am lost. Any ideas?