On the new WoW HC server, about half way through a run of WC, mobs stopped dropping deviate hides, serpent blooms stopped giving serpent blooms when looted, and the bosses stopped dropping gems. We all got about half way through our quests when this started happening. We would try to loot serpent blooms, but then when the loot inventory popped up, there was nothing there. Other loot dropped off bosses but the gems for the quest did not.
This happened to us today, as well. Lvl 27 hunter and 30 warlock were duoing it specifically for the gems. Only got lady anaconda’s then next two bosses didn’t drop gems, so we hearthed out. Also had the exact same issue with the deviate hides, serpentblooms, etc. All the same as them.