Build mode breaks after placing walls, freezes game/computer

I'm on PC and I don't play with mods or cc.

I was trying to make changes to a build I downloaded from the gallery. Placing and moving objects worked just fine until I put a wall down. Suddenly, I can't place or move anything. When attempting to save, the game froze until I had to force it to close. I tried to troubleshoot it, but after confirming that it only happened after placing walls, trying to exit the game has now frozen my entire computer. I can't even get the task master window to show up over the white screen of death. 

I'll note that I downloaded the new patch right before this happened. I was having no issues before.