No point in posting more information. It does this on every single system I've tried, multiple different Nvidia, AMD, and Intel GPUs/CPUs. Windows 10 and 11.
It's a general failure not tied to any specific cpu, video card, or any other device.
Interesting thread, but not germaine to my situation - I do not have a Nahimic driver installed.
Still tried disabling the GPU on WPF panels, didn't make a difference.
I did figure out a clear series of steps to reproduce: 1) use a fresh clean install of Vegas 20 (with all default preferences) 2) right-click, insert a blank video track 3) Select "Grid" or "Safe Zones" on preview overlays. The overlay will apear. 4) Click the menu header (which is blue) to disable the overlay. 5) Select "Grid" or "Safe Zones" on preview overlays. The overlay will no longer appear. In fact it will never appear again. 6) Verify the menu header is blue indicating overlay is active. 7) Clicking the menu header to enable/disable the overlay also has no effect.