Lost the ability to terraform for buildings. How to get it back?

I used to be able to click, hold and drag up weapons and buildings on uneven terrain, now it seems to be gone. That was pretty important to me. I find it frustrating to have a one-pixel square prevent me from putting, say, a caretaker somewhere, or off of the edge of a mountain, hill or cliff.

Did I screw this up? Is it part of the update? Can we have that be optional for those of us who don't play online?

See this post: https://zero-k.info/Forum/Post/205589#205589