I designed a building to built and exited Build & Design Mode. Afterward (not immediately) I noticed that the build appears to built, while it is not. I have not even chosen the option to build it yet. I can’t seem to access that option anymore either. It basically gave me a free building without construction time. Just to test it, I saved the file and loaded it and it was still like this. I made it a flat roof and I can even start building another building on top of it.
I am using the latest alpha build through steam.
[Here is a screenshot of the building.]