I have read your post several times and now it seems to me, that you have a ToC, but it is without links to the following chapters of your book. Calibre needs links to analyze and build the structure of the eBook.
1. Check the links in your toc.html (either to separate files or to anchors)
2. 'Force use of auto-generated Table of Contents'. See 'preferences.jpg' below.
3. Start building your eBook with double click on your toc.html file.
It will be part of the book. If you click on another file you will only get the metadata toc of Calibre.
If
- the toc.html has no links,
- or you don't have a toc.html file,
- or the toc.html file is listed in the folder with your files at the wrong place, i.e. before the file you click on, then your eBook will consist of that file only.
One of these settings may be the reason for the result when clicking on '1.1 Thing at the Start' in your eBook.
Calibre works well with <h2> as toc.txt (html code) and toc2.jpg (Calibre viewer) show.
The chapter titles in Calibre's metadata toc are the <h2> chapter headlines of the html files (see 10.txt).
You may rename '.txt' to '.htm'.
I have made each chapter a separate file, because I don't like anchors.
Note:
- I use <p><br> to avoid the automatically indented first line in paragraphs in the toc and in first paragraphs in chapters.
- The headline of the Table of Contents is in <p> instead of <h2>, because I didn't want it selected by Calibre for the auto-generated toc again. 'Inhaltsverzeichnis' already means Table of Contents, so it would be doubled.
In stylesheet.css I have edited a new <p class> for it with font-size: 1.34em for the headline.
It's the same size I have used for <h2> in the chapters.
- The links are with: font-color: black; and: text-decoration: none; because I don't like the browser look in an eBook.
NeoOffice: I don't know it, but perhaps you could remove 1. with:
search (1.) and replace (nothing, leave empty).
Good luck!
George