The client shouldn't cause this, like you asked in the post before.
There are some phasing issues with NPC's around the server, and I think they're somewhat hard to pick up sometimes unless the developers or bug testers play the game through, but not in GM mode, so it takes time to fix these.
Thanks for the report, and hopefully there aren't too many more (if any) phasing issues. If you find any more, please report them in the bug reports section to help prevent these problems in future releases.
Worgen Area bug
Last Stand .quest 14222 Ends in Duskhaven after a video sequence. You are in stockades and now a worgen.
King Genn Greymane 36332 SHOULD BE standing beside you with the quest after the prior video sequel where you turned worgen. But when the video ends? He is not showing, or still "phased out maybe?" . (Last Chance at Humanity 14375) But he is missing. [Repeated this with 5 worgen. Same end result til the fix i used] This quest is required as you "phase properly" to continue questing after you accept his quest, and turn it back in to him. Otherwise you stay in the stocks "phased out" even dying, or .tele will leave you "hunched over like in the stockades still" unable to continue. I even did .tele dalaran, and appeared there "still hunched over like in stocks!

lol: I was able to add him (.add npc 36332), and he had the needed quest upon spawning. So it IS in the database. He just needs added properly. My way will work, but it has to be did on everyones repack + he spawns right against your as_ behind you. You are bent over rather awkwardly, and.... Well... you get the picture. It just looks... wrong! lol

After you turn in quest however he is no longer behind you.

Until this is fixed however? Spawning him will work. And he remains spawned, or at least did on my server.