Disappearing ceilings (Build Mode)

I'm having the exact same issue, and its only started happening after the July 1st base game update. Even without mods and with the cache cleared, the problem still occurs. My walls are all the way up, and my camera is set to the tallest it can for the build, yet when I try to add a ceiling, it says that there is a ceiling there, so to make it a completely closed room I have to remove then re-add the ceiling for it to work.