Chayula, Who Dreamt kill doesn't count towards the challenge Complete these Deadly Encounters

I have completed two Chayula Breachstones and none of the kills granted me the completion of the challenge step. I assumed it was just a small bug that happened randomly, but after two consecutive clears and still not having the challenge completed, it becomes clear that there is something wrong with the challenges. I have cumulated 34 challenges so far and it becomes increasingly frustrating that a bug prevents me from completing some of the "easier" remaining challenges. A similar bug happened for the challenge Complete these Encounters IV, in which killing a Breachlord wouldn't grant me the challenge. After 5 clears, the challenge was finally granted to me so it didn't bother me as much. In this case, each Breachstone is worth quite a bit of currency so it is more than just inconvenient.