I have tried to upgrade to the next minor release of .71 and still have the issue.
Its still kicking people out of minecraft
Still happening to me with newest snapshot, also some spawners I had that were working in survival also turned to pigs for some reason.
I am having the same issue running official "release 1.8.1" singleplayer with no mods. It is opened up as a LAN game.
We are using itemframes for our storage chest area; as a result, we have 55+ itemframes up with items in each them.
Well before they started disappearing...
Also, before I forget:
Java 7 Update 67 (build 1.7.0_67-b01)
Windows 7 Enterprise 64bit SP1 (Legit)
AMD FX(tm)-8120
NVIDIA GeForce GTX560Ti
16GB RAM
Well it looks like it was somehow linked to the Nintendo profile. Logged out and back in and fixed..weird