title_body: Indesign -> Kindlegen -> Kindle flattens TOC?
upvoted_answer: It seems that the NCX is limited to two levels of hierarchy. I tested the actual hardware for the Fire HDX, Kindle, and Kindle Paperwhite. They all had the same results. Kindle for PC only shows one level. Lastly, I realized that the multiple-levels displayed in Kindle for PC (in a separate author's book) worked because the author (apparently) submitted a PDF, not an EPUB.