[Quoth]

Soft hyphens are for websites. Ebooks should leave it to the renderer to hyphenate.
There should never be a space on any side of a soft hyphen as the only reason for them is a hint as to where to break in a word. Unexpected never-to-be encountered formatting can break conversions.

Someone has used a crazy tool or formatting of the epub. Fix the epub by deleting all soft hyphens before conversion to docx using the Calibre editor, which should be easy.

Auto-hyphens also need to be off on WP source for creating an ebook and on for PDF, because the Wordprocessor has no knowledge of page width of an ebook, but does have the page size set for a PDF.