It only counted the 2nd time for me. I did it solo so I don't know about the group interaction, but I do think it is glitched. You have to have all enemies reanimate, but very often enemy reanimation glitches out. They flash green, but never actually reanimate. It's a bit ridiculous to make this a part of the daily project when the crucial element (reanimation) malfunctions so often.
The second time, I didn't call in the allies so I could make sure that I don't have any unintentional headshots during the 1st phase, but one of the enemies did a side-roll and I accidentally headshot him. It still counted, though.
I guess it's just up to RNG. This game only does what it feels like, when it feels like doing it.