Same here. I'm really getting sick of High Isle. First I couldn't get Ember because the quest is bugged and it's impossible to finish on most characters, and now the same with Isobel. This is completely ridiculous. The ToT dailies are bugged, the companion quests are bugged, the achievements are bugged, everything I tried to play until now are bugged. I love the region, I'd love to be able to play it, but seems that everything was rushed with no testing at all. I fell like a working tester and I'm paying for this crap.
I'm at the barrier near Wizard's Grotto, quest says 'Talk to Isobel', but she is not there.
Loads of peeps stood at the barrier, can't continue.
EDIT:
Logged out and back in again, then she appeared.