Maxoid, here some more stuff for you:
1 - This stair bug they've posted: The stairs object (not the connecting stairs) don't allow a sim to go down the stairs if another sim is already going down. the same with going up. (This does not affect a sim going down and an other going up)
1 - This stair bug they've posted: The stairs object (not the connecting stairs) don't allow a sim to go down the stairs if another sim is already going down. the same with going up. (This does not affect a sim going down and an other going up)
And thinking about it, I don't think it's all the stairs that do this either. In at least two of my homes, the sims will happily follow one another up and down the stairs at the same time, while in others they get annoyed and stand at the top and whine about not being able to get down. I tend not to use the modular stairs as interior staircases in residential lots - I am talking, then, about variations in the stair case objects in both cases.