The internal links (anchors) to h1 headings recently stopped working in my book. To be clear, the following link does not work (even though it used to work perfectly well):
<a href="#anchor">click</a> <h1 id="anchor">Heading 1</h1>
This also throws errors when I export the book to EPUB. Looking at the EPUB code, it seems that the value in the id attribute (i.e. “anchor” in the example above) is moved to a class attribute, so in the EPUB files I would see something along the following lines:
<h1 id="chapter-3206-section-1" class="section-header anchor">
and then I get a “Fragment identifier is not defined” error in the export.
Has anyone else encountered this error recently?
Thanks a lot