Still happening to me, MCPE 15.4 ios iPhone 6s
With the addition of Name tags, I thought for sure that would solve the problem. In fact, I thought mob-DESPAWNING was an intended element of survival mode. I used 3 name tags that were very hard to find in the world to name some sheep I had found in rare colors so I could always harvest their whool.
I went mining deep, came back and almost all were gone. Nametag did not change anything they still de-spawn and there is no way they got out because I have a very very enclosed space for all my mobs.
I really do hope this is fixed, as it is extremely discouraging.
SIDE-NOTE: Searching for this issue gets little results on the Internet. It's mostly just people making fun of the person reporting, but it is a real issue. I really hope Mojang takes it seriously. I'm at my wits end!
I have lost all of my previously purchased Skin Packs, Texture packs, and Mashup Packs the moment I updated to the new 1.1.0 MCPE on Windows 10 edition. I had the Natural Textures Applied, and when I loaded my Realm, the standard Minecraft Textures were showing. I exited Realm, went to global resources, and changed the texture pack back to standard, then when I went to go re-add the Natural Texture pack, it said I had to buy coins and pay for it again. I paid 4.99 already, I should not be forced to buy it again! I have bought almost all of the texture packs and mashups that have come out, and ALL OF THEM have the little "Lock" icon and say I need to buy them with coins.
This makes the update I was so excited about absolutely unplayable.