When the EPUB created by Calibre is opened in Adobe Digital Editions, the table of contents links work. However, when the EPUB was uploaded to KDP, only one link works (Introduction, below).
Code:
<p amzn-src-id="155" class="calibre21">
<a id="toc"></a><a href="rwy8423619339581237951_5.html#_Toc220497661" amzn-src-id="157" class="calibre13"><span amzn-src-id="158" class="calibre22">Introduction</span></a>
</p>
<p amzn-src-id="159" class="calibre21">
<a id="toc"></a><a href="rwy8423619339581237951_7.html#_Toc220497662" amzn-src-id="160" class="calibre13"><span amzn-src-id="161" class="calibre22">In the Middle of the Night</span></a>
</p>