Any individual listing showing in Audiobook Builder's Chapters section will end up as a Chapter within a built file. The only way to view the Chapters an Audiobook contains in iTunes is to begin playing it and then go up to click the Chapters menu that appears at the very top of the screen (see attached image) while the book is playing.
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On the iPhone, within the Music app, there's no way to view Chapters due to an Apple bug in most of the latest versions of iOS. Basically, the button that looks like it has a bulleted list on it is supposed to bring up the Chapters list, but the bug prevents that from working as expected. Skipping between Chapters still works, though.