i was having a similar but different problem in encore and during overthrows ware enemies were not counting for my quests and not even counting as kills for my guns and not providing exp... so i believe there is a greater underling problem with X on kill overall and the enemies are not attached to a loot pool at all resulting in a zero drop....such things would be hard to test on the player side and could be shadow nerfed on the dev side ez and its not the first time this has happend either....