UPDATE: This issue has been fixed.
If the images were added using “Insert Image” outlined in the image below, the file doesn’t get added to manage files. Because the file doesn’t exist in the course files, the image does not come over with the course copy.
To fix this, always add images using the insert stuff bar of the WYSIWYG/Text editor outlined in the image below.
Unfortunately, there is no way to retrieve an image that was inserted incorrectly. The original file will need to be requested from the instructor that inserted it.