Erm... It's a companion, not an item if that helps. Maybe clear your cache and try and unlock it again by staying in the space the required amount of time?
I also don't have the skull. I have all of the quests on the activity board by the stage checked off, and I have every single other reward in my inventory. But I've got no Skull companion. I've looked in iventory, and rewards, it's just not in either category.
I've been in the E3 2012 booth for over 2012 seconds (worked it out at about 35 minutes) several times, including after clearing my cache, and my avi is sitting there right now, but still no luck
EDIT: oh ok, I can still edit this it's fixed, more details in the next post.
I knew as soon as I posted here, it would work
Came back from being AFK in the E3 booth for another 35 mins, and I got the skull.
I was sitting downstairs on a chair by a screen, then moved to another chair, didn't interact with any kiosks or go up the stairs to the VIP area. Other than that, did nothing special.
I have noticed today that I'm missing the LittleBigPlanet Karting companion that was from E3. Today is the first time I looked for it . I know I completed the relevant task to get it and that I got the message to say that I had got it, but it's not showing up in the rewards list.
Wonder if I am missing anything else?