Recently modifying a roof and found that the builders wands will only orient stairs in the east facing orientation (stairs going up, character facing east). flew around to the other side and tried place stairs for other side of roof and stairs only placed east facing. See screenshots.

I also have had issue with this. The rotation of the stair does not change, always oriented east facing. Pointing the wand at different corners of the existing block will not affect the orientation of the stairs placed.