Dog despawns when quiting the game.

When ever you stand up your dog and then quit the game the dog will despawn. The dogs were both tamed had a dyed collars and were named. His has happend twice with the same result. It is also possible to have them despawn from being too far away when they are sitting down. I don't understand why this is happening. I think its the same as the dogs despawn bug in Java that was resloved. Thank you for your time.