I got a problem when placing the stairs, I don't really know if its a bug or it's supposed to be like that.
When pointing at the front at the stairs in the empty space but at the front at the hitbox the other stairs doesn't put there but down; it only happens when you are diagonally towards the stairs. There's a gif so you can see it more clear.
Thank you for your report!
However, this issue has been closed as Working as Intended. The rotation of the stairs in this scenario depends on whether you are aiming at the upper or the lower step of the stairs when placing another stairs.
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