PC - 3 stun challenge not completing

CyanideBlaze

So I have had farming matches twice now with the challenge selected, and have stunned the killer multiple times. I didn't count stuns the first time around but thought for sure I must have gotten it because I felt it was far more than three, but I counted 4 palette stuns for sure the second time around and the challenge still didn't mark as complete.

These were not custom matches, however it was a legion both times. I don't know if it's a me thing or not, but I am wondering if anybody else has had this problem.

I did other challenges after the second time it happened and they have been getting completed just fine.