IMHO it’s a bug, but perhaps I’m missing something, so please have a quick look:
Ground floor:
everything is fine:
first floor:
looks like a whole, can’t place anything, but can’t build foundation, too:
2nd floor:
??
3rd floor:
??
So this 4-tile-square I can not remove foundation or anything else on floor 1-3, I can not build anything on it, only on ground floor. and I can not build foundation on it on floor 1-3…
It seems to be blocked on any level, higher then ground floor…
as it looks like that square is built fundation on 3rd floor (where I’ve never built anything), I tried to deconstruct it on 3rd floor. Instantly there was another square-tile of fundation on ground floor (!) marked for deconstruction, at that tile in 3rd floor nothing happend.
waiting for my workers, when finished I had a hole in my ground floor fundation AND the 3rd floor-tile looked now like a roof tile, not like fundation any more…
but i still
Marked the two squares with white floor and fundation…
ACEO-13464
Now it looks as if there was a built a fundation square on 2nd floor (I haven’t built there anything, yet), which I can not deconstruct, nothing (visual) happens if I try…