Thanks for the suggestions, Steve. I had already tried exporting as IDML and reopening. It strips the export tags from the paragraph styles, so it exports fine as epub until I reintroduce the export tag to that one problematic paragraph style. But even before I do that, it won't show up as one of the options in the epub export dialog box for splitting the document.
I just tried restoring the preferences and the problems persisted.
I've stripped everything from that paragraph style except for basic character formatting, but it hasn't helped at all. Any other ideas? When you delete a paragraph style and have it reassign all instances to a new paragraph style, does it retain any connection to the original one? I can't figure out why the problem persists even with newly created paragraph styles.
It could be something in your system.
Try creating a new user on your computer, and run InDesign from the new user. I don't see that you specified your operating system but it's pretty easy to do.
I tried on my other computer and had the same problem. Running out of time and options, I ended up creating a fresh new paragraph style, then recreating each chapter title and assigning the new style to it. Works great now. Thanks for trying to help!
I am interested in finding out if this problem has been fixed in CC if if not, making sure it gets fixed in a future CC update.
There were a large number of important changes made to EPUB export in CC (http://helpx.adobe.com/indesign/using/whats-new/_jcr_content/main-pars/download/file.res/I nDesign_EPUB_Changes_from-CS6-to-CC.pdf) so I have a suspicion that it was but I want to be sure.
You're a busy person, but would you be willing to share your original files with us so we can confirm this? Or you could try it using the trial version of CC?
You can reach me at firstname.lastname@example.org.