I think the problem is that the enemies that count are despawning, not that the nuke kills don't count. In the mission where you must clear the platforms and defend the portals, I nuked those platforms, and all the kills counted as DFA kills.
Edit: I believe that the kill description in the upper right corner showed "explosive kill" in this case as well, but the achievement/challenge tracker incremented the DFA count.
I've had multiple instances of DFA Nuke triggering and showing a rather impressive number of Explosive Kills, but when I checked the challenge progress I saw no change. If it is counting Nuke kills then it does it only infrequently, and badly at that.
I tested it out on the platforms again, and it was showing the nuke kills as DFA kills, not explosive. I think what happens when you nuke a street is that the NPCs that respawn in the area are killed by exploding cars, thus you see a whole bunch of explosive kills.
Whenever I nuke an area that's guaranteed to be populated when the nuke goes off, I get the DFA kills.
For the challenge, yeah, it is just counting the Alien Kills for that. There are some issues with Nuke not counting/getting kills those kills though.Well that's another weird thing then, because the only kills that count towards the DFA kill challenge for me are alien kills. Pedestrian and even Police/Military kills don't count, even if I don't go from Nuke height. ONLY alien kills count.
Anything "living" that comes out of a portal should count.Well that's another weird thing then, because the only kills that count towards the DFA kill challenge for me are alien kills. Pedestrian and even Police/Military kills don't count, even if I don't go from Nuke height. ONLY alien kills count.