I don’t remember if others reported it in Beta but it is possible that it was bugged for some at this stage. I didn’t have problems initiating her at the stairs, it was after that everything fell apart.
I know that it has been reported since release and at this time I am unsure about how to get her to progress if bugged, beyond this particular point.
I wish I could offer more, waiting to hear back from a fellow player on the official I’m playing on, they are stuck like you are last I spoke with them.