Heroist, I had the same issue.
I identified 3 reasons:
1. Computer lag (either the CPU or the graphics card is lagging).
2. Game lag (with a large number of mods and maximum graphics settings, individual parts may lag or disappear altogether).
3. Corrupted textures.
2. I cleaned everything up, changed the settings, removed all the mods, but it's not that, unfortunately.
3. I didn't quite understand; can you elaborate?
