epub reflowable settings for InDesign question

When exporting to epub, when it automatically opens up in Apple's Books app or Calibre, for some reason the front matter .xhtml info isn't in the nav toc, even though the material is in the actual ebook. As a result, it opens straight to the Introduction chapter, rather than the half-title page at the front of the book. None of my settings seem to be different than usual. Any insight?