You may have hit upon one of the reasons I've 'remained loyal' to doing EPUB->RTF conversions, apart from being tooled-up to deal with RTF:
- For reasons unbeknownst to me, the output of an EPUB->RTF conversion always has the "Do not compress..." option checked, both before and after I apply one of my templates.
- Whereas, the output of an EPUB->DOCX conversion never has the "Do not compress..." option checked, both before and even after I apply one of my templates.
I'm not sure I can help any further - maybe someone on one of the MS Word specialist (cough) forums, or at stackexchange, knows how to make the setting stick to all DOCX documents.
BR