This is the number one thing that annoys me about so many apps, especially apps with clear use-cases for offline use like listening to music, reading, and learning apps. I don't understand how so many app writers have never gone for a run through a canyon or flown on an airplane. I specifically pay money to SoundCloud for instance just for the "feature" to cache the music locally and somehow it regularly gets stuck clearly from lack of internet. It's probably some metric collection or some other spyware to make sure all the bean counters get their money at the huge expense to usability. Pimsleurs language learning app, and many book reading apps all suffer and all I want to do is not be bored to tears on flights that don't have internet.