I have camped for over 2 weeks now. I have characters covering every spawn point. I am covering 16 hours a day at least. I know its not spawning while I am offline because there are 2 horde that camp it over night and they have been at it for 2 weeks with me.
2 weeks no spawn is not normal, it needs to be looked at.
Maybe just super unlucky with the Blood Seeker bat spawning over and over instead of Aeonaxx? I know they technically share a spawn with each other, although the bat does despawn rather quickly.
Have not had a Bloodseeker spawn either as far as i know.
It should be a level 5 bat that can spawn in any of the locations as Aeonaxx that flies around for a few minutes then despawns.
Same on grobbulus… I’m a new player in cata but have all the adding/macros and it’s been a solid week haven’t seen either. Also have talked to ppl in game that also looking and haven’t seen him
I’ve had bad luck with him. Been searching for almost 4 months on two diff realms, one being a low pop realm, and only seen him twice. 
Meanwhile, it took maybe like a week to get Poseidus and Time-Lost.