This is actually a funky new one to me, but I can only assume it's two things.
Either it's problems rendering these meshes for your computer
Or the files themselves have been diddles around with.
Something you should try is changing rendering mode inside of the options menu and then restart the game, possibly lower the screen resolution and other in game settings. And if not that, try to perform a clean reinstall of the game with a new downloaded installer.
It's pretty much the most basic things you can try, but in many cases this does help.
