We can now join games, however while in co-op mission and you either kill a seasonal enemy(which is an immediate boot) or playing through a mission(seasonal or non) if it is completed you receive the following error:

You have been disconnected from the server. In-game progression has been lost and you will be returned to the Command Bridge. Reason: Timed out.

(You don't return to the command bridge by the way, either character select or full boot to desktop).

There are more than likely other ways to get the error, but this is what my friends and I have experienced so far. We are moving one step forward two steps back it feels like.