In my case it's 3 buildings I made at seperate times. I eventually noticed one had a reference marker intersecting it, so I got rid of that and it seemed to fix it, but now I just went back to the place and it's gone again. This is not consistent either (btw the dissapearance is during gameplay). Sometimes when the buildings dissapear they still have their collision meshes, other times they are just completely gone. Doers ANYONE know how to solve this?