I was wondering if anyone knows how to print saddle stitch booklet from Book File?
I know how to do it from normal Indesign file. However, book file is different since there are so many different indesign files.
The most straightforward way to do this is to export to PDF, then use the PDF booklet printing option in the Print dialog. As you have seen, the Print function from the Book Panel doesn't offer a booklet printing option.
I've been creating a booklet file and adding the other files as pages to it before using the Print Booklet function. If you go to layout > pages > move pages, there's an option to move to another file, which duplicates it into that file. Make sure you move all pages.