Album art on PS3

[tehBIGrat]

Hi

I have an issue with album art.

My music is organised album-artist/album/track.mp3

when navigating 'viewing the list' i can see album covers on left of each track
after selecting a track to play the art dissapaires and only displays the default music note symbol.

this only happens on some albums

all files are tagged using same method
all files in question are mp3

Any help please