Murmur last boss in Shadow Labyrinth drops nothing but has loot in creature_loot_template table.
I have also tried 100x drop rate in configs but no chance.
Also quest (10095)[Into the Heart of the Labyrinth] which requires you to slay Murmur it doesn't update after you kill him.
I spawned manually the boss nearby me and killed him and it successfully updated the quest but still 0 drop.
Looks like I have to stay closer to his body center to see the loot window, but the loot cursors shows I can loot. Maybe creature_model_info incorrect bounding radius regarding its model id?