Earlier today I came across a bounty that was a little confusing. It says to kill three cursed thralls in one melee and live, so I loaded up patrol on the moon but it didn't work. I later found out that the description is missing that you must kill them on the dreadnaut, and you can't kill them at the court of oryx. (Bungie has confirmed this) After you know this, the only thing that makes this bounty difficult is that the only cursed thralls in the dreadnaut are at the boss of the sunless cell strike (please correct me if I'm wrong), where you must have allies assist you unless you are in the nightfall, which will also make the bounty difficult. I was lucky and got the kills first try with randoms, but if you can i recommend going in with friends. I hope this helps!