In Settings > Display screen resolution can no longer be changed. I used to go here and select from the drop down menu whatever resolution I needed but now it just displays my current resolution and is not clickable to expand options.
Edit: I did nothing and it seems to have fixed itself… I tried restarting and reinstalling GPU drivers and the problem remained, then I tried running xrandr once more and suddenly it displayed all the available resolutions, went back to the settings menu and they were adjustable there again too, but this is well after I reinstalled the drivers and restarted and the problem still remained, it just started working again out of the blue, maybe running xrandr once more got something to update?