readfile

This content is included from a separate file (called, in this case, include-file.md) using a readfile shortcode:

Use readfile to add repetitive text to multiple pages.

Headings in read files do not appear in the right navigation.

However, shortcodes in the included file do render correctly:

2.25.1.0

Another heading in the readfile

This heading does not appear in the right navigation.