Lead/Leash breaks on all mobs when (assumption!) chunk is unloaded. Lead is on the ground when I return from trips.

I've reproduced this twice successfully and it seems to be whenever I move far away from the mobs.

Leash_edit.png: Sheep (named 'jeb_') cannot move more than 5 odd spaces away from the pole but still the lead breaks and is found next to him after i return from the mines.

leash3.png: also these horses have had the same thing happen to them.