I don't see the email yet with your configuration... Maybe retry the send.
Have you tried killing the Apple Music app and restarting the device? The Apple Music app is the one actually playing those songs and it has been known to act up occasionally.
Have you physically downloaded the songs to your iPad in the iTunes library or are they playing from the cloud. If you haven't downloaded them, you might try that as well.
What version of iPad and iOS are you using?
Have you tried running it on a different Apple device?