I experience this issue on two O/Ses: Ubuntu 20.04 LTS; Nvidia driver 440.100; Linux kernel 5.4.0-42-lowlatency;
and Linux Mint 19 (Ubuntu 18.04) Nvidia driver 384.130; Linux kernel 4.15.0-112-lowlatency on the same PC with
GeForce 1060 6GB.
There were no such issue with some older version of Nvidia drivers (pre 384, I don’t remember exactly)
Games: TeamFortress 2, CS:GO
Two monitors are connected:
Secondary: Asus VG248QE (1080p) located on the left,
Primary: LG 27GL850 (1440p) located on the right.
I also experienced this issue if the left (secondary) monitor is Samsung 931BF (1280x1024).
I start OpenGL games on the right (primary) monitor fullscreen with native resolution 1440p. All works fine until I temporary minimize the game by Alt-Tab and and then maximize it back. In such case OpenGL viewport on the monitor actually has the dimensions of secondary (smaller) monitor (see the photo in attachment). It is not possible to play the game anymore until it is instructed to change it’s resolution. In-game mouse almost doesn’t work as mouse clicks are not correlated to the cursor position.
This issue appears only if primary display is on the right side of secondary. If I swap them (in settings) – all works fine.