Actually this is the reason I uninstalled withMP3, I was having problems seeing the playlist too. With PocketMusic I didnt have any trouble tho, so thats just the one I'm using right now, I think they both just need an update badly. Sorry I couldnt help more on that.
Hmmm, now that I think about it, the playlist might not just display the title of the mp3, but some more info encoded into the mp3 like the title of the track and the artist, etc, from when the file was created, and some ppl do or dont add this info, and so it might not display anything, or display something funky, this is the only thing I can think of at the moment. I might send PocketMusic & withMP an e-mail and ask them about it.
Laterz!