I took a quick look at the epub with Sigil (version 7.30) and it was not happy with the ebook. Partly since the only file that has the the DOCTYPE declaration is the first file, all the other files are missing it which causes Sigil to whimper about the s that are scattered through the book.
Code:
<?xml version="1.0" encoding="utf-8" standalone="no"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN"
"http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
Code:
<?xml version='1.0' encoding='utf-8'?>
<html xmlns="http://www.w3.org/1999/xhtml">
Also, Sigil complained about the stylesheet.css and page-style.css files since the lines in the chapter files did not include the path.
Code:
<link href="stylesheet.css" rel="stylesheet" type="text/css"/>
<link href="page_styles.css" rel="stylesheet" type="text/css"/>
Code:
<link href="../Styles/stylesheet.css" rel="stylesheet" type="text/css"/>
<link href="../Styles/page_styles.css" rel="stylesheet" type="text/css"/>
This is likely caused by the directory structure of the .epub file having all the files in the root directory other than the meta-inf directory which is "Not A Good Idea" while Sigil wants to convert to a standards compliant directory structure.
Though neither of these two should have kept the ebook from showing up on your reader.
I've attached the Sigil modified version. Please let me know if it is any happier on your Mini.
Regards,
David