The Numbered Headings app works with the default Confluence export.
When you export a single page, the headings are numbered the same as on your Confluence page.
When you export a document with multiple pages, the numbering continues across these pages. See the Confluence documentation on exports for more information.
If you use the Scroll Exporter app by K15t, Scroll Exporter takes control of the numbering. This behavior is implemented in consultation with K15t.
You can include numbering in the Scroll Exporter using a template that supports numbering. One of the default templates that supports numbering is titled Documentation.
For more information about numbering your documents when you use Scroll Exporter, please turn to the K15t documentation.
Not sure if you are using the default Confluence exporter or the Scroll Exporter?
If you do not see an icon next to the Export menu item, you are most likely using the Confluence export.
This behavior was introduced in Numbered Headings version 4.0.6.