Tall buildings

[RightDeve]

The impassable/rough "cap" is to ensure cover and concealment are good, because it is still "part" of the building.

And I tried with copy pasting to remove outlying slopes or any other methods I could think of. Nothing. It may appear correct at first glance, but once the map is scrolled (refreshed) the height values show flat building. The single hex containing the hill is key.

Imp's suggestion gives food for thought that maybe some (new) building types have obstacle height quite tall. Thus in itself, it's already tall, without underlying terrain being tall (which AFAIR was what Mobhack said what makes it difficult is that buildings always flatten small patch of elevated terrain).