Strange!? It sounds similar to another issue. When you have already run a ConDoc export, dropped drawings into your LayOut presentation, then go back to SketchUp, work on your model, run another ConDoc export, then drag more drawings in. The issue is that the reference in the presentation is out of date, but the reference in the scrapbook is the latest and greatest.
Try updating your SketchUp reference before running the second ConDoc export. Or at least update it before you start dragging and dropping drawings from the ConDoc Drawings scrapbook.
Feel free to give me a shout at 720.443.3242 to chat about it.