AutoCad :: Drawings Lose Extents If Published?

Using Full Autocad 2013, no extensions.I have a directory full of 25 drawings, P&ID's to be exact. I've done all the drafting on them, and I need to publish the set. I used to publish them 24x36 to our plotter, but we have started sending out large plot jobs, so I need to publish to PDF. This normally isn't a problem at all. I set up the first drawing's layout tab to print. Everything is good. Preview it, all is good.

I open the publish box, add all the drawings layouts, use the page setup from the first drawings layout, select publish to PDF, set them to go to my normal folder, and publish. The drawings all publish, and everything is correct except that they all, instead of centering on the page, they center horizontally but go to the bottom of the sheet vertically. So I have a two inch margin on the top of the drawing and .5 inch or so on the bottom. I'm assuming this means that the publish can't find the drawing extents (we use plot to extents, center plot). So I go into all the drawings, zoom extents in all the layouts, and still it publishes the same.

Is there a variable I'm missing? If I plot just one it works and the plot is dead center of the page, publish more than one and it doesn't work.