nope, you're not missing anything. the library only scans for audio files, not playlists.(ok you could argue a cuesheet isn't an audio file but you know what i mean )you can still load your m3u playlists via the file menu and play them as you would in any other software. once loaded, they are saved internally in foobar's own native .fpl playlist format. if you were to re-arrange/remove/add tracks, it wouldn't touch your m3u file unless you explicitly go and save over it.