My friend and I were playing a survival world (hosted on my computer, she was playing on her iPad with me over Xbox Live) and we each tamed a cat. She left after a while of playing. Shortly after, I left the game too. When we came back on the next day, her cat was gone. We tried teleporting it to us with /tp @e[name=Winslow] @s (that was the cat's name) and vice versa, teleporting us to it; we just got an error message that no entity existed in that selector. We then relogged, and Winslow was back! We went on with our day, and logged off after. That was yesterday. Today, Winslow is gone and won't come back no matter how many times we relog.