Hi Kovid & Quoth!
Tried THIS code below using
only odd pages,and code cleaned up a bit.
Same error:
ValueError: The number of header/footers pages (381) != number of document pages (762)
<header style="justify-content: center; color: black; font-size: x-small;padding-top: 5px;padding-bottom:10px;">
<div class="odd-page"><p>Part _TOP_LEVEL_SECTION_, Chapter _SECTION_</p></div>
</header>