atjnjk,
I must eat crow and render my humble apology to Daniel_9 and mrannah for any confusion I have caused. Thank you for pointing out my error.
What I said ONLY applies to conversions of news articles or other downloads via a recipe, in which case clicking the "Do not add Table of Contents to book" has no effect whatsoever and can not be changed by the user at the present. Previously, Calibre did allow application of the removal of such a TOC from downloads but no longer does so.
What I said does NOT apply to the conversion of books already existing in one format or another and being converted to a MOBI format. I tried it with a downloaded article that had a TOC. Once downloaded, I converted it to an EPUB and then using "Do not add Table of Contents to book" converted it back to a MOBI. The TOC WAS removed just as you said.
Thank you for catching this and bringing it to my attention.
Again I regret any confusion I may have caused.
