For the High Conductor step of the Symphony of Death exotic quest line where you kill the named enemy in the Scarlet Keep Strike. It appears that if the player with the step does not deal damage to the High Conductor before another fireteam member kills it, that player is not rewarded with progression. Had this happen to me where my 2 teammates found it first and burst it down before I could get a shot in. They both got the quest completion in the activity feed while I did not. Guessing the trigger logic is probably checking for player damage on death rather than presence in activity on death. Could also be the intended behavior I suppose, just logging here in case it isn't as its not a great player experience (from my perspective at least haha)