My wife is struggling with Crossfire kills while in her headhunter/Determined build.

As title, she's been tryna progress through the journey but something about that build just will not let her get Crossfire kills. Its the standard Perfect head-hunter/Determined build with the armour on kill backpack for survivability. She's using White death, Scorpio and a random pistol with determined, yet none let Crossfire trigger. I've watched her do it correctly and it isn't triggering. I've done the same thing in a few different builds and it works for me fine (didn't test my PHH/D build). Grouped or solo.

Collateral, assists and priority kills are all counting.

She's just changed to her skill build and it's working as intended. She's happy she's found a solution, but just a heads up if anyone else is struggling. No idea what causes it, though.