Q: Family Sharing music issue

I have an iPhone 6 and a Macbook Pro that are both updated to the latest software versions.  I have family sharing turned on on both and have been able to successful download some music on both devices. There are many songs that I try and download though that are not successful. On my iPhone it just says its unable to download at this time, on my mac it acts like it downloaded and then when I go to play the song it tells me that the computer is not authorized and the box to authorize pops up.  This only happens with certain songs other songs play just fine and my computer has been authorized with my apple id forever.  Please Help!