Notes:
1. I encountered this issue on PC.
2. I was playing with my boyfriend. Both on PC.
3. I was playing as Drizzt, he was playing as Bruenor.
4. There really isn't a work around, or at least not one that we've found.

Steps:
Running through the missions; playing the game as normal.

Result:
Upon completing the mission, we look at the rewards, we both press enter and hold to take us back to town. Except I never go. Tells me "failed to join session" when the countdown stops and never does anything more.
I can hit esc and leave, but tells me I will lose all progress.

I tried closing the game through ending the process, but had no progress when I logged in - no loot, no attribute points (from the shrine in the mission), and my boyfriend keeps getting ahead of me in experience because he's keeping his for completion, and I am not.

This has happened 3/4 times and thusly has become unplayable for me. I tried solo to catch us back up, but it's so slow and not really enjoyable as a solo player so I just quit playing the game. I legitimately cannot progress any further.

We love the series and would love to play the game, but boyfriend tried last night on his own on Wolfgar and got stuck, and was forced to force quit losing an hour's worth of progress.

Expected Result:
I would end up in town with my loot and rewards from completing the mission.

Or that it would try again to send us to town in 30 seconds/1min, but once it tries the one time, that's it. You go or you lose progress.

Maybe a "Finish mission" button that pops up at the end that we can trigger, that we can hit again if we "fail to join session". Something.