Hello.
Some weeks ago I caught Lupos and have sort of been leveling him back and forth. I managed to get him up to 53 when he mysteriously disappeared in the stables. I tried everything getting him back, but to no avail. I've been in contact with the gamemasters about this subject and from what I can understand they are looking in to it at the moment. The official report was that they "fixed" this issue 2 weeks ago, but for some reason it keeps happening.
Anyway, after losing this first Lupos at level 53, I spent an entire night camping him to catch him again. After successfully doing so, I've spent the last few days leveling him. About 10 minutes ago, after the new one reached level 51, I hearthstoned to Undercity to swap him out for my level 60 pet, because I was going UBRS.
It then happened again. Poof, gone! That's two Lupos pets gone forever for some unknown reason.
The point of this story is watch out, it's one hell of a nasty bug and it could quite possibly happen to you. Has anyone out there experienced anything like this?