Thank you very much for that!
I think I know the reason why there's a pagebreak between "Chapter I" and "An Unexpected Party". The default chapter detection scheme checks for the words chapter, book, section and part inside <h1> and <h2> tags. The part in An Unexpected
Party probably triggered this, hence it was recognized as its own chapter. It should be easy enough to get around this by changing the regular expression any2epub uses or by disabling automatic chapter detection.