So I'm back expanding my castle after a long time and some of the towers I've build pre-7.0-patch have a "block-glich".
This thing is impossible to remove by any means and it counts as a physical object because I cannot complete the sides of my tower.
The only thing I can do is this:
but it's not what I want.
I tried to deconstruct some blocks and in some towers it works but in others (like in this case) not.