I was building some pens last night for cows and faced this problem. The pen is a 2 deep hole in the ground with a fence around it. I lured a cow in and went to get another and when I came back the first cow was gone. Got the 2nd one in and went for a third and when I came back the 2nd was gone.
At this point I started walking around the area and slaughtering every animal I found. My cows no longer despawn.
Here's my theory: I believe there is a passive mob limit in a given area. Once that limit is reached or exceeded, the newest animals in that area will despawn. I had lured my cows from a few chunks away so them become the new entity in that area and when I left, they despawned. When I reduced the number of passive mobs then my animals were no longer above the limit and could stay. I would assume the xbox just doesn't spawn new passive mobs once the limit is reached, but when we breed or lure animals we are temporarily exceeding the limit which the xbox is correcting by despawning our animals or limiting our breeding until the number is brought down to the limit.
If you are having trouble with animals despawning or can't breed your animals then I think you need to start slaughtering all the animals in the area you don't want. There will always be animals you can't even see that have wandered into caves or fallen into small lakes under the surface.
At this point I started walking around the area and slaughtering every animal I found. My cows no longer despawn.
Here's my theory: I believe there is a passive mob limit in a given area. Once that limit is reached or exceeded, the newest animals in that area will despawn. I had lured my cows from a few chunks away so them become the new entity in that area and when I left, they despawned. When I reduced the number of passive mobs then my animals were no longer above the limit and could stay. I would assume the xbox just doesn't spawn new passive mobs once the limit is reached, but when we breed or lure animals we are temporarily exceeding the limit which the xbox is correcting by despawning our animals or limiting our breeding until the number is brought down to the limit.
If you are having trouble with animals despawning or can't breed your animals then I think you need to start slaughtering all the animals in the area you don't want. There will always be animals you can't even see that have wandered into caves or fallen into small lakes under the surface.
And they say cracked is whack.. Pffft...