I can't believe they did that

I was building a cave in the Siege editor that started at the "Hidden cave" node, and couldn't get it to connect up to the far exit (back to the same region). I discovered that there's a half-unit offset between outside and inside, so the Hidden Cave can only connect to a dead end (or another Hidden cave to reverse the polarity again, but two the same just ruins the point of it).

Every other piece fits the grid except that one! WHY?!