I have a mobi file with 2 level - table of contents when it is opened by Calibre as the image below.
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Then, I send this file to my kindle by sendtokindle app on my pc.
After that, the TOC is messed up as the image below. All links are jammed into "Front Matter".
![]()
Anyone knows why and how to fix it?
Thanks!

Then, I send this file to my kindle by sendtokindle app on my pc.
After that, the TOC is messed up as the image below. All links are jammed into "Front Matter".

Anyone knows why and how to fix it?
Thanks!