Please can you check what is wrong? The Extension show an error message, this is reproducible.
The bug appears also when rendering that as the only page of a book.
The page is part of the new book
http://www.mediawiki.org/wiki/User:Wikinaut/Books/MediaWiki_Developer%27s_Guide
where I noticed the problem today in the generated PDF.
Version: unspecified
Severity: normal
See Also:
https://bugzilla.wikimedia.org/show_bug.cgi?id=45856