I went through all code comparing v05 to v06, but I couldn’t find any graphics-related changes. Does anyone else get this problem with v06?
The long-term plan/solution is to upgrade the game to use DirectX 11. DirectX 9 has already exhibited multiple incompatibilities (including the “Esc doesn’t pause game” bug). It will take a solid week’s worth of work, however, so I can’t spare the time to do this in the immediate future.