Originally Posted by pdurrant
OK, I've taken a look (moderatorial superpowers). I don't know what, but some setting in the conversion has caused every single paragraph to be output in its own HTML file.
I hope that this info will let the calibre people tell you what to change.
Since you had the crystal ball
It seems like there is a Page-Break-before coded at the Paragraph level.
ticking do not split on Pagebreak (EPUB Output Conversion setting) might cure
these results (but leave a messy size break only book)