I realize this is an old thread, but I have the same/similar problem. I created a Collection, stuffed it with photos I wanted to use in a book, then went to the Book module. At some point I saved the book. At some point(s) I left the Book module to visit some other Collections and Folders and find more photos, etc. I went back to the Book module. Over a few hours, I rearranged and resized photos, laid out my cover, added Page Text and Photo Text, and finished about a third of my book. Then, tired after a long day, I quit Lightroom.
I came back to it a few days later, and cannot see any of my work! When I clicked on the Book module it took me to an Unsaved book, which had some(all?) of the right photos, but none of my edits or text. I saw the saved book, clicked on that; it has the same(mostly?) set of photos, in a different order, but again, without any of my edits or text.
Is there any place I can see a list of all saved books? apparently not. I manually stepped through all my Collections, and Collection Folders, trying to see whether I'd saved the book in another place; no luck.
Are the changes actually lost when you switch away from the book, or exit Lightroom, without explicitly saving? if so, that's a horrible design. (Actually, the whole Book module is terribly confusing, and poorly designed.)
Am I SOL?