So I was playing Spartan Ops, Episode 3 Mission 5, when the Jackal Rangers came in. I thought I killed all of them, but it turns out that one had gotten stuck in a ravine on the other side of the cliff. We go all the rest of the way through to the part before the airstrike, and then its tag popped up. It was on near ground level, behind their cliff. I tried to fly over with the Jetpack, but there was a low ceiling invisible barrier. Completely impossible, grenades couldn't even reach it. We spent an extra 7 minutes on this one part. Eventually, we all just quit out one by one, and got no EXP for our hard work.