I started playing a few months or so after the original dropped. I never got this achievement in the new one, even when we killed them with almost 11 minutes to spare (public instance). Sad to see it not in the patch notes 😕
I've been plagued with this issue since around the FCU, but turning the Geforce Experience in game overlay off fixed it (at least I hope so, haven't dropped below 10 FPS in 2 days).