@MF Not a bad theory, but it is incorrect. Whenever something has disappeared, I have always been online. Sometimes, even within the loaded chunks of the wolves!
@ Joel Fivat I do not believe this relates to that problem.
A. All these wolves were tamed on a new 1.4.2 world.
B. None of them were growling or had been killed/ hit by another player or myself.
C. I could make them all stand/ sit no problem.
No. It is a personal server I run off my computer with no more than 5 people on at any one time. In this particular case, I was on alone. One day my dogs were there, I checked back a few days later and every single one was gone. This has happened several times. Back in 1.2.5 I had a Bukkit server and I had 1 group of 15 dogs and 3-4 groups of 4 despawn on me. I thought it could have been Bukkit itself or one of my plugins so I paid it little mind. Now the exact same thing is happening on a 1.4.2 default server. I lost one dog at first, then went out and tamed a large group but they went away as well. Only thing I can figure is breeding farm animals in the same loaded chunks may be reaching the mob limit at night when hostiles spawn, and despawning the dogs enmass to free up the mob count.
Same problem for me as well.
Snapshot 18w50a
Seed: 6063057163609804162
[media]Flew out in Creative to ~8500X, ~70Y, ~20Z and got an End Gate in the outer islands to spawn. It also teleports back to the obsidian spawn platform.