A job mate who works at my place making ebooks from InDesign has faced a trouble making different levels in navegational TOCs in ePubs:
He usually makes one long InDesign document and then builds an epub from them without much trouble. However, he met a rather troublesome job —full of hyperlinks and references that was a bit too demanding for his system—. So he splitted the job in a set of documents and gathered them in a book. So far so good till he tried to build the TOC for the epub, where he met these two troubles:
1. labels of the chapters of the TOC in the epub are not the headlines that have the "headline" style applied, but the are labelled as the name of the file (without the indd extension); that is: instead of having "The Day Bilbo travelled", for instance, we have "bilbo_travel".
2. Where we have designed a two levels TOC with styles headline_1 and healdine_2, navegational TOC inside the epub uses just the headline_1 level —and that using the name of the file and not the proper text (the heading using the designated style).
Using: InDesign CS6 (updated) in a Macintosh.
Do you have any idea where is the trouble? We cannot see where to touch... Desperatedly started to investigate tampering the epub with Calibre / Oxygen... :/
Gustavo (Posting from Madrid)
Make sure that on EPUB Export Options/General/Navigation you select TOC Style.