[scruffs]

Hi. I'm old and wrinkly in terms of writing books, but new to epub.

I have a completed epub that passes validation (as does the CSS). It displays okay in Kindle Previewer.

I want to check it in Apple Books on my Mac.

So I followed Apple's instructions (unzipped epub and added the .epub extension to the folder).

In Apple Books I select:

Advanced > Add EPUB to library as proof

and select the folder I just created (nnn.epub).

But nothing happens. The proof is not loaded, and Apple Books just sits there. No error messages - nothing.

Am I missing something?

Thanks in advance.