The mystery continues...I did try adding the landmarks section & with and without the ids & classes. Then, in the midst of moving computers, when I opened the file on my new mac, I saw an encryption file that I hadn't seen before. I deleted it, and the TOC suddenly worked. I'm not convinced this was actually the problem though, as I have another book with the exact same problem, and deleting the encryption file did nothing. :-/ Completely validated by idpf AND iTunes, and no luck getting the TOC workable on iPhones & iPads (desktop iBooks reads it fine though!).
In both documents its the only nav declared, the ol is set up to specifications, and the toc appears in the menu, but just keeps routing to the first page. This second book has a more barebones set-up, with no ids or ol classes:
<?xml version="1.0" encoding="UTF-8" standalone="no" ?><html xmlns="http://www.w3.org/1999/xhtml" xmlns:epub="http://www.idpf.org/2007/ops">
<head>
<title>toc</title>
</head>
<body epub:type:"toc frontmatter" id="toc">
<nav epub:type="toc">
<ol>
<li><a href="../Text/CoverImage.xhtml">CoverImage</a></li>
<li><a href="../Text/The_Missing_Link.xhtml">The Missing Link</a></li>
<li><a href="../Text/Copyright.xhtml">Copyright</a></li>
<li><a href="../Text/Dedication.xhtml">Dedication</a></li>
<li><a href="../Text/About.xhtml">About</a></li>
<li><a href="../Text/Table_of_Contents.xhtml">Table of Contents</a></li>
<li><a href="../Text/Preface.xhtml">Preface</a></li>
<li><a href="../Text/Acknowledgments.xhtml">Acknowledgements</a></li>
<li><a href="../Text/Section_1_Web_Development.xhtml">Section 1 Web Development</a></li>
<li><a href="../Text/Section_1_Assessments.xhtml">Section 1 Assessments</a></li>
<li><a href="../Text/Section_2_Document_Markup.xhtml">Section 2 Document Markup</a></li>
<li><a href="../Text/Section_2_Assessments.xhtml">Section 2 Assessments</a></li>
<li><a href="../Text/Section_3_Scripting_Languages.xhtml">Section 3 Scripting Languages</a></li>
<li><a href="../Text/Section_3_Assessments.xhtml">Section 3 Assessments</a></li>
<li><a href="../Text/Section_4_Persistent_Data_Storage.xhtml">Section 4 Persistent Data Storage</a></li>
<li><a href="../Text/Section_4_Assessments.xhtml">Section 4 Assessments</a></li>
<li><a href="../Text/Section_5_Tying_it_Together.xhtml">Section 5 Tying it Together</a></li>
<li><a href="../Text/Glossary.xhtml">Glossary</a></li>
</ol>
</nav>
<nav epub:type="landmarks">
<h1>Guide</h1>
<ol>
<li>
<a epub:type="cover" href="CoverImage.xhtml">Cover</a>
</li>
<li>
<a epub:type="toc" href="toc.xhtml">Table of Contents</a>
</li>
<li>
<a epub:type="glossary" href="Glossary.xhtml">Glossary</a>
</li>
</ol>
</nav>
</body>
</html>