Jackie, I took one of the "misbehaving" ones, unchecked the NO SVG COVER and PRESERVE COVER bits and did an EPUB (original) to EPUB conversion. Did not make any difference.
Below the procedure indicated by you for the book in question. Mind you that it looks like you are much more literate in "computer science" than I am. Do hope the abacadabra below makes some sense to you. Thanks a lot!
<?xml version='1.0' encoding='utf-8'?>
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/>
<meta name="calibre:cover" content="true"/>
<title>Cover</title>
<style type="text/css" title="override_css">
@page {padding: 0pt; margin:0pt}
body { text-align: center; padding:0pt; margin: 0pt; }
</style>
</head>
<body>
<div>
<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" version="1.1" width="100%" height="100%" viewBox="0 0 575 882" preserveAspectRatio="none">
<image width="575" height="882" xlink:href="cover.jpeg"/>
</svg>
</div>
</body>
</html