Happend to me couple of times - at entrance Mammon is targetable, inside he is not. WTF?
http://sh.st/rvxIF
Tried with a restart?
This one was bugged, but at the same time I found him in another location.
This case was like the 3rd time i had this. If you wanna know I have one char registered to cata (dwarf on movie) and I logged it speccialy to check if mammon has offhand option. On other noblessed char I was looking for BOM, trying to cach his target before diving, and If I catched him on target I'm normally expecting him to be on his place.
This is not that important case, only annoying. I think second mammon (at the begining of the server there was two cata-mammons) so this is probably just side effect of the 'fix'...
(http://i61.tinypic.com/2dagn5s.jpg)