I was checking out the new XM playing and did not see them in the drawer so I thought it did not work. It just turned out that capitalised extensions do not display in the drawer. Would be a simple fix...I need to learn Cocoa 
1 2008-01-04 09:58:21
Topic: Uppercase file extensions do not work. (3 replies, posted in Bugs)
2 2008-01-04 09:51:55
Re: audio files are not visible in the list (15 replies, posted in Squashed Bugs)
I had this problem, too. I believe that the issue may be related to me sorting and dragging columns. I was sorting on 'Track' when this occurred.
Deleting preferences did the trick.
OS X Leopard
Macbook Pro