When an author imported a Word document (.docx), the images she added using Smart Art did not come through the import to Pressbooks.
What we know
Images and other files added to the Media Library in Pressbooks must be JPG, PNG and GIF files in order to display.
The current Word import routine built into the Pressbooks Textbook plugin does not (cannot) include all markup language used in a Word document because there’s just too much of it.
The Word import routine recognizes standard markup language for lists (bullets and numbers), headings, textboxes. Formatting and layout created in a Word document that uses proprietary markup language (vs. standard markup language) is unlikely to make it through intact from the Word document to a Pressbooks account.