I'm a idiot because you're wrong? Makes sense, I guess.

You have to be close to the boss or deal the final shot. I did it and every time it counted for two people in the fireteam but third [ sniping far away] got nothing

That makes sense because there was at least three times we killed the walker in a strike that I didn't get credit for in the bounty. I finally completed that bounty yesterday but was wondering what was up.