Overset text in story editor but not text fr

After I placed at the top pages of the book that I had JUST got done formatting, the rest of the book disappeared from the text boxes, but it's in the story editor. The editor shows a very long red line to indicate that it's all overset, but when I apply the overset text to the beginning of the book, nothing shows, so it's just an endless expansion of blank boxes.

In another thread, I saw someone mention exporting it to an IDML, which I did, but it just brought me back into InDesign as the same result.

I'd really not like to waste more time looking for a solution—and worse, having to reformat the entire book again.

Any advice?