Hi, i've the same problem, only heading1 are shown in TOC in azw3. żIt's not possible to change this?. In the conversion process add a header depth in conversion options to show in TOC headings up to level x. Now only heading1 is shown so if you put 3 headings 1 to 3 are shown in TOC.
I don't know the exactly format, i assume it's not a navpoint systema like in epub, but if h1 are shown because the TOC takes them from the sections, can the conversion transform headings up to level x to 1.
The real problem is that i now have to reedit the epub changing headings greater than 1 to 1 to be shown in the toc, it'll be great if this is done in the conversion process.