Be careful on this mission I got a major bug with it. I was on advanced diff and was having trouble... I beamed out and set the diff to normal and back again. After I did that I could no longer stop the crew members... just the Devs. it made the mission almost impossible.
You have to be careful with your resetting as well; the first time i did it, there were 2 starfleet officers who were invincible and kept chasing me down to the respawn point. When i left and re-entered in hopes of fixing it, the "Break up the bar fight" got that check mark next to it, but ALL of the brawlers involved were now back alive and invincible. Made it a whole lot harder to take out the devidians with a bunch of invincible enemies chasing me all over the station.
Same here - the first time a Starfleet Medic went down to 40% and that was it - but seemingly because I didn't stop the bar fight (even though at that point it was just between my away team and that damned medic) I wasn't able to access the rooms with the rest of the Devidians. I restarted the mission and a Klingon and four Starfleeters were then invincible... Probably still in that bar fighting even while I type this.