i have the same problem and there is also the npc in raid zone that i can not see as well. some of the other guildies were able to see it but i could not and its not a grafic issue because i would have been able to assist for target but he simply did not exist ( was on 92 prov with all TS quests done) while other guildies could see him.
would be nice to get these taken care of because it is setting some poeple really behind