Did you fight her before? Because I think thats the thing that caused it. And sorry for late reply, I was busy D:
I could try to see if I can make her revive after you kill her (alongside some other bosses, like I did with Sergal), if I see more people wanting me to do that. But yeah, for now it is best to avoid fighting her. Sorry if I didin't make it clear (I'm aware not everyone would read the book I put on there.)