Brad - In Windows, I have been using OneNote Md Exporter, found at GitHub - alxnbl/onenote-md-exporter: ConsoleApp to export OneNote notebooks to Markdown formats
This works perfectly for me. Through trial and error, I found I needed to change the following settings:
/* Add at the beginning of each page a YAML header that include Page metadata (cf YAML front matter | Assemble ) /
"AddFrontMatterHeader": false,
/ Remove multiple consecutive linebreak generated by PanDoc /
"DeduplicateLinebreaks": false,
/ Prevent generation of more than 2 linebreaks in a row */
"MaxTwoLineBreaksInARow": true
This little utility was originally publicized on reddit. It works seamlessly - way better than the built-in OneNote export or Joplin import. It's definitely worth a try!