Mobs moving, not in buildings pens ect

Mobs are moving on loading world
1st run 0.15.0 and once loaded my villagers for my iron farm where no longer in their pocket a 1 x 2 x 10 area, but scattered every where. I put some back, killed rest and then closed mcpe. Once I reopened the world again they were not in the pocket, but scattered.
Similar issue happens with my cows sheep ect fenced in, on loading world they are no longer in the pens.
Also with my chicken farm they are no longer in the walled area a 2x 2 x 2 box.