Is this 12 page spread because there are only a few records (or even just one) on a page, or some pages only have a few fields on them, or nothing, - or what? You could be describing a margins or printer paper problem because of someone's settings. I can't recall if output to pdf is based on printer settings or not. Might be worth looking at. Perhaps you designed the report based on 8 1/2 x x11 and they're set to A4?
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.