I always thought it was simply a bug that it did not drop loot. Couldn't even imagine a rational, logical, developer not having it drop loot given the historical trend for loot triggers in the previous raid. It's basically Gatekeeper part 2. Gatekeeper drops loot so Deathsinger should drop loot. Am I right? Hope they do fix this bug. After beating it several times there's really no reason to keep on doing so without some reward.