I tried killing her so I could resurrect her after speaking to Isobel to see if that helped, because some people said this worked for them.
It didn't for me.
This was one of dozens of workarounds I tried and nothing did.
She is now in my camp (after she said she was leaving) and even if I say to join me, she says 'ok' but doesn't actually join. What's also weird is whenever I talk to her, the rest of my party is in the background like a cut scene almost.
Anyway, I can't see how this isn't a bug and HIGHLY annoying because of the implications in Act 3.