I just split the file into three, as you advise. Title, toc, main. In the Previewer it all works perfectly, it starts at the start of Chapter 1. But on the Kindle it starts at the beginning of the TOC.
This is my tiny test file, it only has a one line title, a toc, then two chapters each of just a few lines (for testing font sizes). I could easily upload it here.
I welcome any more suggestions.