In addition - if I rename the .docx file to .zip and explore the contents I can see all the required files are existing in a readable state in the media folder but for some reason the link to them in the document is broken.
PHPDocX appears to be downloading the images correctly but something is going wrong when it tries to link these streamed images. I've got the fully licenced copy so I can attempt to debug your code.
If I find anything I'll let you know but any hints or ideas would be helpful.