I'm in the same situation as you.
I had one register after finishing the Darkblade strike and was thinking to myself, yeah I definitely didn't melee a cursed thrall during that.
I first just tried to load up the fist of crota mission, since there is plenty of cursed thrall and you can separate them out very easily and none of them registered.
Seems like both of Eris' quests/bounties are bugged...the thralls and then some taken war thing which I have no idea what the hell to do for it either.
English
-
Holy crap, I thought I was stupid. I've been trying to figure out what the hell this taken war quest was. If you figure it out tell us.
-
Taken War? Get a fire team, go to the specified planet, wait until Taken fog appears on the screen, kill as many Taken as you need until it says, "A Taken lieutenant is corrupting the land." And kill it, then it will say, "Darkness rises! A Taken zealot arrives to claim you!" And it will spawn an Ultra, kill it. It will not summon the zealot unless you have a fire team, which is stupid, considering people one man Crota's End!
-
Charlie14575 is saying it actually has to be done on the Dreadnaught. Like you, I went straight for the Fist of Crota mission. I guess it was by doing that strike on the Dreadnaught you happened to get one. Nice. At least now there is less confusion.