Using the command line, --markdown doesn't seem to work anymore. In the original pdf, each chapter was marked like this C H A P T E R 2 with each letter in Chapter seperated by a space. Hueristic processing wouldn't detect the chapter headings, so I converted the book to txt and did a replace and replace the original C H A P T E R with ##CHAPTER . I then used the command line to convert to epub. It would not detect the chapters. This is strange. This has always been a fail-safe method in the past. Of course in past versions of Calibre GUI, I have always been able to to check the box "Use markdown", now this feature is absent. There is a markdown Section, but no check box.
I am using version .7.47
Thanks,
Paul