I found this thread when faced with the same problem as in the original post. ie "When I convert any document - docx, odt, epub, azw3, txt -
to mobi format my chapter headings in the book will display with a leading number:
1. Chapter 1
2. Chapter 2"
I'm using Libre Office 7 to edit the docx file, and calibre to convert it to mobi format.
On attempting to edit the Heading 1 styles I was unable to change the Numbering Style because it was ""disabled when chapter numbering is assigned to a paragraph style".
To cut a long story short, I found LO 6.4 help page
https://help.libreoffice.org/6.4/en-...l?DbPAR=WRITER
"To Add Automatic Numbering to a Heading Style
Choose Tools - Chapter Numbering, and then click the Numbering tab.
In the Paragraph Style box, select the heading style that you want to add chapter numbers to.
In the Numbers box, select the numbering style that you want to use, and then click OK."
which can also be used to Remove automatic numbering from a Heading Style, which then removes the unwanted numbers on chapter headings when converted to mobi.