Thanks for the response. Here's the content.opf file, as it appears in Sigil:
Code:
<?xml version="1.0" encoding="utf-8"?>
<package version="2.0" unique-identifier="uuid_id" xmlns="http://www.idpf.org/2007/opf">
<metadata xmlns:opf="http://www.idpf.org/2007/opf" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:dcterms="http://purl.org/dc/terms/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:calibre="http://calibre.kovidgoyal.net/2009/metadata">
<dc:language>en</dc:language>
<dc:creator opf:file-as="Claymore, S.F." opf:role="aut">S.F. Claymore</dc:creator>
<dc:contributor opf:role="bkp">calibre (5.11.0) [https://calibre-ebook.com]</dc:contributor>
<meta name="calibre:timestamp" content="2021-06-27T06:35:57.662918+00:00" />
<dc:identifier id="uuid_id" opf:scheme="uuid">7c8732d4-5fdd-44a3-9780-324bf16b4843</dc:identifier>
<dc:identifier opf:scheme="calibre">7c8732d4-5fdd-44a3-9780-324bf16b4843</dc:identifier>
<dc:title>Champion's Rising 3Ed</dc:title>
<meta name="calibre:title_sort" content="Champion's Rising 3Ed" />
<dc:publisher>S.F. Claymore</dc:publisher>
<meta name="calibre:series" content="Champion of Psykoria" />
<meta name="calibre:series_index" content="1" />
<dc:date>0101-01-01T00:00:00+00:00</dc:date>
<meta name="cover" content="cover" />
<meta name="Sigil version" content="1.2.0" />
<dc:date xmlns:opf="http://www.idpf.org/2007/opf" opf:event="modification">2021-06-27</dc:date>
</metadata>
<manifest>
<item id="cover" href="cover.jpeg" media-type="image/jpeg"/>
<item id="titlepage" href="titlepage.xhtml" media-type="application/xhtml+xml"/>
<item id="id243" href="index_split_000.html" media-type="application/xhtml+xml"/>
<item id="id242" href="index_split_001.html" media-type="application/xhtml+xml"/>
<item id="id241" href="index_split_002.html" media-type="application/xhtml+xml"/>
<item id="id240" href="index_split_003.html" media-type="application/xhtml+xml"/>
<item id="id239" href="index_split_004.html" media-type="application/xhtml+xml"/>
<item id="id238" href="index_split_005.html" media-type="application/xhtml+xml"/>
<item id="id237" href="index_split_006.html" media-type="application/xhtml+xml"/>
<item id="id236" href="index_split_007.html" media-type="application/xhtml+xml"/>
<item id="id235" href="index_split_008.html" media-type="application/xhtml+xml"/>
<item id="id234" href="index_split_009.html" media-type="application/xhtml+xml"/>
<item id="id233" href="index_split_010.html" media-type="application/xhtml+xml"/>
<item id="id232" href="index_split_011.html" media-type="application/xhtml+xml"/>
<item id="id231" href="index_split_012.html" media-type="application/xhtml+xml"/>
<item id="id230" href="index_split_013.html" media-type="application/xhtml+xml"/>
<item id="id229" href="index_split_014.html" media-type="application/xhtml+xml"/>
<item id="id228" href="index_split_015.html" media-type="application/xhtml+xml"/>
<item id="id227" href="index_split_016.html" media-type="application/xhtml+xml"/>
<item id="id226" href="index_split_017.html" media-type="application/xhtml+xml"/>
<item id="id225" href="index_split_018.html" media-type="application/xhtml+xml"/>
<item id="id224" href="index_split_019.html" media-type="application/xhtml+xml"/>
<item id="id223" href="index_split_020.html" media-type="application/xhtml+xml"/>
<item id="id222" href="index_split_021.html" media-type="application/xhtml+xml"/>
<item id="id221" href="index_split_022.html" media-type="application/xhtml+xml"/>
<item id="id220" href="index_split_023.html" media-type="application/xhtml+xml"/>
<item id="id219" href="index_split_024.html" media-type="application/xhtml+xml"/>
<item id="id218" href="index_split_025.html" media-type="application/xhtml+xml"/>
<item id="id217" href="index_split_026.html" media-type="application/xhtml+xml"/>
<item id="id216" href="index_split_027.html" media-type="application/xhtml+xml"/>
<item id="id215" href="index_split_028.html" media-type="application/xhtml+xml"/>
<item id="id214" href="index_split_029.html" media-type="application/xhtml+xml"/>
<item id="id213" href="index_split_030.html" media-type="application/xhtml+xml"/>
<item id="id212" href="index_split_031.html" media-type="application/xhtml+xml"/>
<item id="id211" href="index_split_032.html" media-type="application/xhtml+xml"/>
<item id="id210" href="index_split_033.html" media-type="application/xhtml+xml"/>
<item id="id29" href="index_split_034.html" media-type="application/xhtml+xml"/>
<item id="id28" href="index_split_035.html" media-type="application/xhtml+xml"/>
<item id="id27" href="index_split_036.html" media-type="application/xhtml+xml"/>
<item id="id26" href="index_split_037.html" media-type="application/xhtml+xml"/>
<item id="id25" href="index_split_038.html" media-type="application/xhtml+xml"/>
<item id="id24" href="index_split_039.html" media-type="application/xhtml+xml"/>
<item id="id23" href="index_split_040.html" media-type="application/xhtml+xml"/>
<item id="id22" href="index_split_041.html" media-type="application/xhtml+xml"/>
<item id="id21" href="index_split_042.html" media-type="application/xhtml+xml"/>
<item id="id3" href="images/LandOfBeastsBookFunnelB%26W.jpeg" media-type="image/jpeg"/>
<item id="id4" href="images/PsykoriaFinal.jpeg" media-type="image/jpeg"/>
<item id="id5" href="images/RealmscoreFinal.jpeg" media-type="image/jpeg"/>
<item id="id6" href="images/RoyalSigrunFinal.jpeg" media-type="image/jpeg"/>
<item id="page_css" href="page_styles.css" media-type="text/css"/>
<item id="css" href="stylesheet.css" media-type="text/css"/>
<item id="ncx" href="toc.ncx" media-type="application/x-dtbncx+xml"/>
</manifest>
<spine toc="ncx">
<itemref idref="titlepage"/>
<itemref idref="id243"/>
<itemref idref="id242"/>
<itemref idref="id241"/>
<itemref idref="id240"/>
<itemref idref="id239"/>
<itemref idref="id238"/>
<itemref idref="id237"/>
<itemref idref="id236"/>
<itemref idref="id235"/>
<itemref idref="id234"/>
<itemref idref="id233"/>
<itemref idref="id232"/>
<itemref idref="id231"/>
<itemref idref="id230"/>
<itemref idref="id229"/>
<itemref idref="id228"/>
<itemref idref="id227"/>
<itemref idref="id226"/>
<itemref idref="id225"/>
<itemref idref="id224"/>
<itemref idref="id223"/>
<itemref idref="id222"/>
<itemref idref="id221"/>
<itemref idref="id220"/>
<itemref idref="id219"/>
<itemref idref="id218"/>
<itemref idref="id217"/>
<itemref idref="id216"/>
<itemref idref="id215"/>
<itemref idref="id214"/>
<itemref idref="id213"/>
<itemref idref="id212"/>
<itemref idref="id211"/>
<itemref idref="id210"/>
<itemref idref="id29"/>
<itemref idref="id28"/>
<itemref idref="id27"/>
<itemref idref="id26"/>
<itemref idref="id25"/>
<itemref idref="id24"/>
<itemref idref="id23"/>
<itemref idref="id22"/>
<itemref idref="id21"/>
</spine>
<guide>
<reference type="cover" title="Cover" href="titlepage.xhtml"/>
</guide>
</package>