[trekky0623]

I don't want to post copyrighted material, so I made a test file to demonstrate the issue. It has html files labeled "TestFile,A-01.html", etc.

When loaded onto the Kobo Aura as is, it should show Chapter One, Chapter Two, and Chapter Three at the bottom of the page for the chapter title.

If you then remove the book from the Kobo, convert it with Calibre ePub > ePub, then add the book back, it will no longer show the chapter titles at the bottom of the screen.

Remove the file again, and edit the toc.ncx file to replace %2c with , and add the file back to the Kobo. The chapter titles will reappear.

Now, to be fair, ePub validator does complain about these commas, and the book should probably not have commas in the filenames. However, I feel that Calibre is still breaking functionality here by replacing characters with URL codes in filenames listed in the toc.ncx file. If the publisher is putting commas in their filenames, maybe it should be left alone?