After helping on a team with a player who needed to unlock hm earlier today, my understanding was that they would stay and help me get the penance king fight successfully completed. What actually happened was that everyone but the person they were helping in normal mode left once regular mode waves were completed.
This is another example of why attempting group content is so exasperating.
I'll add you, Dremix. Maybe we can find three more people who also need to get the requirement done. All I ask is that the team perseveres until everyone gets it done.