I'm using an iTunes library song as an alarm sound and the song does not play on wakeup. What's going on?

Due to changes in Apple's iCloud library settings that were introduced with the release of Apple Music, you should make sure that your selected song is available for use offline. In order to do that:

1) Open the Music app on your device
2) Navigate to My Music
3) Find your selected song and tap the menu button (indicated by "...")
4) Select "Make Available Offline"

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