Looks to me as if its treating every paragraph as a chapter, and that may overflow something. Have a look at the Structure detection settings, I would try setting the
Detect chapters at (XPath expression): back to the factory defaults, which is:
Code:
//*[((name()='h1' or name()='h2') and re:test(., '\s*((chapter|book|section|part)\s+)|((prolog|prologue|epilogue)(\s+|$))', 'i')) or @class = 'chapter']
Added - Or maybe you styled every paragraph in Word as a Header 1 or 2, if so change them to Normal style
BR