Wrong heading numbers in PDF export

When using the Numbered Headings Application, the heading numbers from the PDF export are different than those from view mode. Follow these steps to reproduce:

• install the Numbered Headings Application
• create a wiki page with this content:

  = Header 1 =
  
  == Header 1.1 ==
  
  (% data-xwiki-rendering-protected="true" %)
  === Header without number ===
  
  === Header 1.1.1 ===
  
  (% data-numbered-headings-start="10" style="--numbered-headings-start: 9;" %)
  == Header 1.10 ==
  

• active numbered headings
• notice the heading numbers from view mode
• export to PDF

The heading numbers from the generated PDF are very different than the ones from view mode.