1. I get invited to group.
2. I zone to Poitain after the group leader has entered the instance (to ensure going to the correct guild city).
3. I arrive in Poitain successfully and I am prompted that I am in a different instance from my group and I am asked if I would like to change to their instance.
If I say Yes, then it starts to load up the correct instance but then hangs on a white screen with some very vague textures. The only way forward is to quit AoC, restart, log in and then I am back at point 3 above. Selecting Yes again, just keeps hanging the game.
At the moment, when I am invited to a group going to Poitain, the only successful way I have to get to the right instance is to say No when prompted to change instance and then to ride to a Rez pad and change instance manually. We have even tried making me leader and letting me zone to my guild's city instance and have the others follow me there. In that case, the people following me to the instance had the same problem.
So it seems auto-switching of instance to get everyone in a group to the same instance as the leader is borked (at the very least for Poitain).