Kindle Create's "Suggested Chapter Titles" window lists every heading and sub-heading from my BookyAI DOCX, not just the chapters. What can I do?

Update to BookyAI version 1.9.10 or later and export the DOCX again. Kindle Create builds its suggestion list from anything that looks like a chapter title: heading styles, large centred text, short bold lines. Since 1.9.10 only the chapter openers (and the front and back matter titles, such as Introduction or Glossary) use the top heading style. Sub-headings inside a chapter are left-aligned, only a step larger than the body text, and use Word's Heading 2 and Heading 3 styles, so Kindle Create no longer offers them as chapters. In the suggestion window, keep the chapters and matter sections you want and untick anything else; Kindle Create only asks once per import.