Does anyone else have this glitch where after a certain time of messing around in a worldspace, stuff will just start to disappear, but when you double click on the blank space where it was, it's actually there, but then in game it isn't there? Sounds a bit confusing so http://s20.postimg.org/gfyb20x31/Untitled.png
The only way I've been able to fix it is to close the CK and discard any unsaved work. It's pretty annoying.

I think its something to do with memory. Just hit F5 to refresh the render window and it'll fix it.

Could be a mod corrupted your save