Images from included pages are not viewable in a Word export

When exporting a page to Word that includes other pages, the regular inline images in the included page will not be visible in the export.

Steps to reproduce:

1. Add a new page.
2. Include another page that contains inline images.
3. Save the page.
4. Go to "Tools" -> "Export to Word" and open the resulting *.doc file in Word (Windows or Mac).

The image will not be visible, and just show a blank line in its place.

Looking at the underlying HTML code, the images from the included page do reference base64-encoded data, but the encoded data is not actually included as part of the file.