The talent of this Exotic Shotgun is "Melee attacks Instantly Kills non Elite enemies" where it have a damage cap of i think around 100m but the issue in escalation in higher tiers is that NPC have way more health and armor than this where its talent fail to eliminate them. Even the non elite NPC's who have the damage reduction only takes around just 20% damage to their armor or health.
This thing needs to get fixed as its clearly making the talent not working properly in this game mode which is clearly unintended.
If Dev can fix the unintended loot dropping from box as Priority, this also needs to be fixed ASAP in next update as priority.