Two ePub books that I've bought won't open in Books.app in macOS Mojave 10.14. The books have social DRM (personal information added to the content of the book), and I don't think this should be a problem for Books.app. If I rename the epub extension to zip, then I can unzip the file using the
unzip command. Using the Finder doesn't work somehow. Other books open normally.
Looking at the contents, I see that it uses XHTML inside an OEBPS folder, while other books use HTML in an OPS folder.
What is the reason that Books.app doesn't open these ePub files? I can read them OK with Calibre.