I have a similar bug on a laptop with both Intel UHD graphics and an NVidia GPU. Without Nvidia loaded, behavior on unlock is as expected. With nvidia modules loaded, even though not used for display, something is disabling the display _after_ I unlock the screen (screen comes up from sleep and is enabled until I unlock. So not a driver issue I think. I don't think it's a black window either, because
chvt 7 && sleep 3 && xrandr -d :0 --output eDP-1 --auto works to recover from it (from a console terminal). Something chooses to disable output to the display, on _restore_. I haven't found what it is though. (sleep 3 isn't necessary, just for my own sanity to see the pause and avoid other races if chvt returns a bit early.) -Drake
