I think I was one of those reporting this issue before.
But anyways, I did some more testing. The issue with disappearing heads seemingly only affects female lizards in sitting positions. I tested this with male lizards and both male and female humans. Don't know about dwarfs. In addition, there are several Elf NPCs that sit down once in a while without any issues. When the game entered EA the bug also affected other races; this issue seems to be fixed.
The bug regarding disappearing heads when under status effects (like 'Diseased') seems to be fixed however.
