Pretty sure there are other threads about this, and I will upvote them, but literally created an account just for this.

Disconnects during a mission are one thing, my buddies and me can reconnect, but we clicked the final altar and the end of coop missions 2 and everyone dropped.  No XP.  No rewards.
Very frustrating to lose all the effort and waste my time making no progress.  I have limited time and this is just silly and ruins my experience.

Please fix!   I really enjoy this game and encouraged others to jump in with me.  Want to not be punished by stuff like this.