Help please. I am using the included music app on my NW-ZX2 and have just loaded a lot of music onto a sd card. All works well apart from the fact that album cover art is not showing on about 10% of the albums. Using the media go app on my pc to manage the music all the albums show their cover art fine.

Using Google play music on the Walkman, all the cover is shown fine. Using Media Monkey all the cover art is also shown.

I'd prefer to use the Walkman app so why is it not showing some of the cover art?

thanks