What happens if you purchase songs in TTR3 but they don't download?

I purchased a number of track packs for TTR3. They didn't immediately download. I went back to the track packs, and TTR3 recognizes that I have purchased them. "You own this track pack." It then provides a link: "Tap to download and play." I "tap" the link, and a popup comes up saying "Preparing..." (with the beachball waiting icon). The popup just dissolves, and that's it. No download. No error. No confirmation. No nothin'.
I've restarted TTR3. I've restarted my iPhone. I've not synced.
Username: Perdendosi.

Thanks!