Album art for local files is missing on my IOS devices

[antiduplicity]

I have several playlists that are a mix of local files and spotify files.  All of these mixed playlists are availab le offline on my iMac and on my iPhone.  When I check the "available for offline use" on my iphone things chug for a little while and the non-spotify files appear on my phone, but without album art.  None of the local files have album art on my iphone.  Now on my iMac they have the correct album art and it looks great.  The album art is not being transferred to my iPhone.

I have included a screenshot of the file on my iMac with album art and oplaying on my iphone with no album art.  

Any thoughts.  Am I holding it wrong or soemthing?

Michael