Guild Wars 2

This happened yesterday evening (11 pm GMT +1) while doing AC story mode.
Party: Guardian, Elementalist, Engeneer (the three of them who have already completed the story), Ranger and Mesmer.
Server: Aurora Glade

We did the instance just fine until when we had defeated Kasha. When the battle ended some pink beams appeared on our mesmer and reached both heroes (rytlock and Eir) and blocked them. When the mesmer walked another random beam started also to strike party members blocking their movements. We don’t know this could have happened. the mesmer had to log off and log in again, the problem with party members was resolved but the heroes remained stuck for the entire instance. Only Eir move to Ralena and Vassar chamber ‘cause she had to talk there, but both didn’t attack.

Confirmed. There is a bug with Kasha Blackblood that allows Mesmer’s to steal her abilities using “Arcane Thievery”. I’ve managed to have it happen twice.

It’s novel, but somewhat annoying as your abilities stun your teammates and will render some of the NPCs immobile for the next fight.

In the interim I recommend you refrain from using Arcane Thievery in this encounter. If you do, log out and log back in to make the bug go away.