I've posted the requested sample file at this location:
http://www.newselfpublishing.com/private/MouseDeer.mobi
This is a preview file downloaded direct from Amazon KDP. When unpacked with KindleUnpack 0.65 (AppleScript version), the folder mobi8 > OEBPS > Images is empty. The same folder is empty in the output from unpacking the AZW3 file.
Also, when the AZW3 file is viewed, the images disappear about a third of the way into the book, replaced by empty boxes. I found these same results whether viewing in Previewer, Kindle for Mac, or Fire HD. By contrast, all images display as expected when viewing the preview file before unpacking.
When a preview file was generated for the same book in Previewer 2.922 on the desktop and unpacked, the same image folders were empty. However, the AZW3 file showed the images as expected when viewing.
I'm on Mac OS X 10.6.8 with Python 2.7.6.