Build Mode not working after placing stairs or platforms

Since the new expansion release, I can't finish a proper build. Often after placing stairs or building a platform, any following action in build mode is impossible. I can't delete walls, I can't place objects. If I try to save the game, the saving button starts rotating for an infinite time. The game stays responsible, but save never happens. 
I play on PC. I do not use any mods or CC, but I have a few EP.