Custom Headings Don't Appear In Navigator, TOC

I’ve been making a PDF E-book, and am having trouble getting my chapter headings to show up in the Navigator and Table of Contents. Despite having used LibreOffice for over two years and basically growing up on Microsoft Office, this is my first time using the Styles and Formatting functionality.

For each of twelve chapter titles, I’ve applied a paragraph style which is a child of the built-in Heading 1, as well as a nice-looking custom character style. I previously had these showing properly in the Navigator window, and had each chapter wrapped in a section as well, but on exporting to PDF found that LibreOffice had deleted all of my page breaks between chapters. So, I removed the sections and replaced the page breaks, and now my headings aren’t showing up in the Navigator nor the table of contents built from recognised headings.

I’ve tried a few solutions including setting a chapter title’s style back to default, then again to my style, to no avail. I’m at a loss for just what might be wrong, and so any help would be appreciated.

Styles will show in the TOC and the navigator only if they have an “outline level” assigned. There are two ways of assigning a level to a style:

  1. The preferred method: Tools → Chapter Numbering → Numbering tab → for each level select a paragraph style (defaults are “Heading #” for “Level #”)
  2. Modify your style definition → Outline & Numbering tab → set a level

Note that both methods are incompatible: if a style gets a level in “Chapter Numbering,” the corresponding option in the style definition will be greyed out.