This problem is also happening on my realm. I had Single Player Sleep, Armor Stands, and Mob Heads packs enabled. Now, mob heads have disappeared from my game and were replaced with unlabeled black "spawn eggs". The custom recipes others have mentioned are also appearing for us as well.
Amber Harover
This problem is also happening on my realm. I had Single Player Sleep, Armor Stands, and Mob Heads packs enabled. Now, mob heads have disappeared from my game and were replaced with unlabeled black "spawn eggs". The custom recipes others have mentioned are also appearing for us as well.