I was fighting against Hex when she runs out of screen and never comes back. I waited for some minutes and still nothing and this is the same result for the other times I tried fighting again against her. Basically it means that till now you can't progress further.
EDIT: I got past of it by trying to block her and staying near her if she tries to do that. Still try to fix that bug pls cause it took me a lot of tries to get past it.