I didn't read any of the AHM after the actual Prime victory, so I don't know if they explained it in there or not. But I just read Last Stand of the Wreckers #1 and I was disappointed to not see my favourite Autobot as part of the crew. I then read Bumblebee #2 and see him in the background. Is there any explanation or is this just something the writers haven't cared about enough (yet?) to talk about?