I’ve been trying for the last hour, following instructions I found online, but nothing’s working. My book is just one long continuous chapter with no chapter breaks/headings. I tried putting the text files in folders and naming the folders “chapter 1,” “chapter 2,” etc., but that didn’t work either. Is there a definitive/authoritative tutorial I can follow step-by-step for every detail I need to know for compiling Kindle/mobi ebooks?
Use a page break as a separator for every Chapter.
You have to be sure that the proper section types are being assigned to your chapter documents, and that those types are being assigned to the right section layouts at compile time. When you bring up the compile window, the types are displayed on the right, and the section type assignments are displayed in the middle.
This is explained in the interactive tutorial project (under Help), in the “Get It Out There” portion of the binder.