This is for regular inline images, not generated images (CONF-25599).

Steps to reproduce:

1. Add a new page.
2. Insert an image by going "Insert" -> "Image", then upload an image and attach it.
3. Save the page.
4. Go to "Tools" -> "Export to Word" and open the resulting *.doc file in Word for Mac 2011.

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

Opening the same *.doc file in Word running on Windows will show the image.