We improved our EPUB export in CC and continue to do so for the next CC update.
I would like to see if this still fails in CC so we could fix it - would you be willing to share your files with the EPUB team for our internal use only?
Even if it now works in CC we should be able to tell you why it is crashing in CS6.
Architect, InDesign Engineering
I am happy to share the file. It is 25 mgb, I could send by dropbox, please
You should try the steps in the link Peter posted.
That will help narrow down the problem.