Only 7 of the 56 selected variants can be processed... why??

I've highlighted all of the images in a session (56) and am trying to process them out to low-res JPEGS. Why will it only allow me to process seven?

I may have just answered this, but here are a couple of more clues to the puzzle. Seven of the images are ranked with one start and it was in "ranking" order. Although all of the images were highlighted, it was only processing the ranked images.

One more question... If I'm processing images in one session, can I leave the session and go to another and will the images still process? I don't think so, but I just wanted to check. This could be a problem.

Thanks,
dw