I've got two ImpExtStairs02 arranged in a small staircase - when I move from one cell to another and back again both pieces of stairs disappear. Any reason for this? Bug maybe? I have to keep putting them back which is very annoying but then they'll vanish again when I load up a different cell and back.

CK doesn't always render everything after you jump back into the cell from another one in which case try hitting "F5" to get it to redraw.