Mercedes Audio 20 and artwork

[bensonhedges]

I just bought a new car with Audio 20 sound system and although it plays all my music from either the iPod or usb stick fine, some albums appear without artwork in the display even though all albums in iTunes have the correct artwork attached and it is embedded in each track in the Music folder on the pc.

 

Of course I've googled many websites and Mercedes forums but, whilst there are many tutorials on how to add artwork initially, there seems to be a dearth of information on this problem. Anybody else had it and can shed any light please?

 

Thanks very much.