Walls are not built or are built incorrectly.
Walls & Watchtower:
He doesn't build a roof or walls for the Watchtower. So he builds one wall, but he simply doesn't build the others.
If I want to build a wall, the first thing I do is to build the lower frame. My char then hammers, but no frame appears! Not at the bottom or at the top.
Then I noticed that he is building the wrong building plans. Instead of building a frame at the bottom, he builds a platform.
I also completely dismantled the single wall and rebuilt it in the same place. The same result.
That's super frustrating, as you can imagine.