This issue appears on my Radeon RX 580 and my friend's nVidia Geforce 1080ti. It is a difficult issue to replicate, and it only occurs some of the time. It seems to only occur after I've been playing for more than 10 minutes when I play the level from the start. Moving the player 1 start to the center of the map and starting in the affected area doesn't seem to trigger the issue. After experiencing the problem, then leaving the area and returning, the problem does not recur all of the time. Sometimes it shows up after I leave, sometimes it doesn't. Also, the menu graphics will not appear while this issue is present. I can still pause the game, and moving the mouse causes the menu sound effects to play back. The difficulty of replicating the issue is that I don't have the time to start from the beginning of the map and hope that it reappears. It really only seems to show up about 1/4 of the time, making it hard to troubleshoot.
Here is what the problem looks like:
Spoiler:The issue 'flickers' on and off when stationary and rotating. It seems to appear only when I am looking in certain directions, but that direction isn't consistent between times that the problem occurs. sometimes looking north causes the issue, sometimes looking south causes the issue.
Here's an example of standing in the same place and turning:
Spoiler:Any help or troubleshooting tips are greatly appreciated.