The other day, I wanted to download some new songs to add to my starred tracks since I was taking a long trip. I downloaded them on my computer and then I synced it to offline mode on my iPod so I wouldn't waste my iPhone battery, and all the songs worked fine on my iPod. The next day I tried to listen to the songs on my iPhone because it showed they had syncd offline, but the new songs wouldn't work, only the old ones I had would work. I tried re-downloading them on my iPhone, but that didn't work. The only time the new songs work offline is when I'm connected to the Wi-fi or I turn on my cellular data. But the songs still work fine on my iPod when I'm offline.