EPUBs not showing in Preview pane

[adelpit]

EPUBs are not displaying in my preview pane. EPUB is checked under Document Files in Previewed Formats. I'd like to get it working. Other document formats are displaying OK.

My default EPUB viewer is Calibre Ebook Viewer. It works OK but I'd prefer to use XY.

[admin]

Select such a file, then paste this script line into the address bar and press ENTER: previewcheck;

Post the returned report.

[Horst]

Calibre doesn't bring any Explorer Preview function
so XY will not display a preview for it.
There is no OS native epub previewer and also no public available epub preview tools.
Using a tool like DarkThumbs you can get a thumbnail view of the cover page.