Offline songs sometimes/dont work all have been downloaded.

[Johnnyhated]

All the songs on my play lists have been downloaded,and listened to offline. Playlist songs I've listened to numerous times now have no green arrow, sometimes even though in offline mode they're greyed out they'll still work. So offline works sometimes /sometimes not . I have changed no setting. It seems like evry other time I get on this darn thing there is some kind of issue. I want to start paying for premium after the free trial bUT don't want to pay for something that only works half the time.