Recon Trifecta Codex Challenge Help and or Clarification

For the Recon Trifecta Mastery Challenge does defeat 3 runners in one activation of pulse mean down or eliminate or both? This is one of the last codex entries I have left and I've noticed previous challenges with variations of defeat down and eliminate have not been 100 percent true for the challenges to track. Meaning I have only downed runners when the requirement said to eliminate them and its still counted. This one has stumped me for months at this point any help would be appreciated. I've seen videos now of people unlocking the challenge while only downing the enemy runners as well as some where they only kill them after their teamates downed them. Ive also seen a little bit of both. I've failed to unlock this now for months even having played multiple games where i most definitely should have met the requirments according to these videos one way or another yet the game saysI still have not. I have the Vidmaster title for petes sake I feel like I shouldnt be having this hard of a time lol. Is it possible i'm bugged? Thanks for your time.