Co op kills not counting towards milestones

Update: this bug is evident when the Heavy is using the same blaster in multiple, consecutive, rounds. 

If the blaster is changed at every match the milestone does “appear” to progress but it’s not correct and it’s still under-counting the kills.

I’ve earned dozens of T-21 unlocks this evening, in testing, alone but it’s for nothing because the progress counter doesn’t constantly record the kill counts.