You cannot go on the low half part and they do not move items up.

The first issue is only present in 1.11, will work on fixing. I've been unable to get items to work properly with the ramps, but am actively working on it.

Items will work on Conveyor Ramps in the next update. I probably won't have the stair model itself fixed for 1.11 however.

Fixed in version 1.1.14. Stair model and everything.