Restarted but made not difference. This problem occurs (at least) in folders that are accessible from a media server. I will try now to mount the disk.
Ok, the bug seems to exist only when accessing folders from the “Media Servers” menu. After mounting the network disk and navigating through the Library the single song selection works.
Hiya - this problem seems to occur when the music folder you select (I also have my library ordered by folders, not artist, title, etc) has a sub-folder: in your case “Artwork” - get rid of this subfolder and it should solve it.