Comment 2 for bug 1960822

calibre does not advertise handling for any ofthose file formats. I
suggest you uninstall the distro based calibre and install the official
binary from https://calibre-ebook.com/download_linux

I have no idea what the ditro package does. The official binary
advertises support for only the following, which are all very much ebook
formats:
text/html;application/x-mobipocket-ebook;text/rtf;application/ereader;application/x-mobipocket-subscription;application/oebps-package+xml;text/x-markdown;text/plain;application/epub+zip;application/pdf;application/vnd.oasis.opendocument.text;application/x-cbr;image/vnd.djvu;application/vnd.ms-word.document.macroenabled.12;application/x-cbc;application/xhtml+xml;application/x-cb7;application/x-cbz;application/x-mobi8-ebook;application/vnd.openxmlformats-officedocument.wordprocessingml.document;application/x-sony-bbeb;text/fb2+xml;x-scheme-handler/calibre;

 status invalid