I've re-read through the posts about this issue today and decided to test the latest 16.2.3 release. The issue persists. This time I tested two different systems (both linux) :
1 - My desktop with AMD CPU and Nvidia 1070ti.
2- My laptop with Intel CPU and Intel Video.
On both systems, the issue is present - (putting to rest the thought that it's GPU drivers on the host machine.) To reproduce, create a new virtual machine, enable accelerate 3d graphics, and do a fresh install of 20.04. Open a terminal or a text editor and you'll see it right away.
If you open a terminal and run glxgears the issue totally goes away as long as it runs. It appears that keeping the display busy prevents the issue from happening. Some people have reported doing odd things (voodoo) that can make the issue go away (at least for awhile.) I believe the busyness of the system has a lot to do with it.
