I wish I could help, but I'm having the same problem.
That whole fight with Konstina has me pissed off. We're ordered to kill her, right? Well, here's how it went down for me:
First, I charged over and surrounded her in the first round. Ensnared her and stunned her by the second round. Then Odil comes over and what does he do? Knockback. Twice. So now she's unstunned and free to run and halfway inside her base. So I teleport next to her and surround her again. We reduce her to zero hit points and keep hammering away. Apparently, you can't kill her! Then, some numbnuts magic user on Odil's forces charms her. So now she can run free and I can't attack her. Two rounds of running (with me keeping pace) and she just disappears.
I finish helping Odil clear out the base, but when I'm done killing the bad guys there's no Odil, no Kontina and no way to get through the gate described in the previous post. Odil is not at his fort or his hidden camp. The folks at Avadon are still telling me to go help Odil, so the job's not done as far as the game is concerned.
Can anyone help?