I've had to shorten all long filenames to get Maemo to use them. Files never showed up when they were too long. Try shortening the long file names to less than 16 characters and see if it doesn't solve your problem.

Yeah, I know. My whole music collection and movie collection is too long, too!

If anyone figures out how to stop maemo from dissecting the thousands of media files on huge drives full of ID3 tags and stop thumbnailing 15000 Jpegs, rendering it useless, please lemme know...