Amazon developers don't seem to understand the concept of 'offline'. When I am in airplane mode, the app just spins and spins. Come on Amazon, the music is on the SD card. And, now, it apparently isn't. I find my library is all messed up. I have double instances of albums. And some of it is gone from the SD card. Worst part is, I am unable to redownload it. And, some of the double albums can not be deleted. Short of real time streaming, the app is fast approaching useless.