Recently I have been trying to figure this one out. And I think I know what the problem is.
From what I had seen and am guessing, this milestone only works against actual players (Bots do not count). And in order for it to count, You have to Pull and kill the enemy with one swing of Your lightsaber.
I tried it out on Heroes vs Villains - against all the odds and F-bombs I kept dropping due to players basically gangraping 4 vs 1 - and yesterday on Galactic Assault. And I managed to occasionaly get +1, or even +2.
So next time You try to get that milestone, try pulling near dead enemy and then finish him with one hit of the lightsaber (Frenzy doesn't count, I guess).
DICE Team
