There are following statements in the package.opf file:<package xmlns="http://www.idpf.org/2007/opf" prefix="ibooks:
http://vocabulary.itunes.apple.com/r...xtensions-1.0/ calibre: https://calibre-ebook.com" version="3.0" unique-identifier="bookid">
<metadata xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:dcterms="http://purl.org/dc/terms/" xmlns
pf="http://www.idpf.org/2007/opf" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
I have modifed manually the EPUB3 file described in scenario 2 by replacing opf metadata with the ones corresponding to the scenario 1. And Pocketbook recognized series information this time!