When I plug in my iPod Classic to my car radio system, it doesn't show album artwork but when I plug in my iPhone it does. Is there a default I need to change?
Might have to do with how artwork is stored. iTunes can store it in the mp3/aac/whatever music file or in a separate database.
I noticed when exporting often the art is not included. A way to force iTunes to include the artwork in the file is to edit the file info in iTunes - like e.g. add a comment. Then the tag is rewritten with artwork also included.