Windows 8 64x
Java 7-21 64x
What I expected to happen was...:
A horse to spawn from the horse spawn egg and to stay spawned.
What actually happened was...:
It spawned and the game removed it less than a second after that.
Steps to Reproduce:
1. Use the Spawn Horse Egg
2. The horse vanishes
Initially I thought that horses are biome bound so I went around though different biomes and tried but the game just removes the horses immediately after they are spawned. I tried a whole set of things such as changing game difficulty, changing gameRule for spawning mobs and so on, but nothing really helped.
I cannot spawn a horse in no way what so ever and make it stay spawned.
Also, I should note that the world is old, created maybe in 1.4 and is a server world.