Fiio X5 Inconsistent Album Artwork Resolution- Advice appreciated

[idjit dragon]

Hi Guys
 
I've tried the usual googling but with no luck.
 
I have an issue with a lot, but not all, of my album artwork displaying in very poor quality resolution.
 
I use Mp3tag to embed artwork in the files.
 
The mp3s and Flacs are a combination of DBPowerAmp CD rips, torrents and purchased downloads.
 
Album art displays fine in Windows Media Player and Itunes.
 
I've looked at the JPEGs themselves and can't see any pattern regarding size and resolution as to how it displays
 
I'm on beta 2.31
 
 
Adele's 21
 
http://i1180.photobucket.com/albums/x407/idjitdragon/20141213_172232.jpg
 
 
Black Sabbath's 13
 
http://i1180.photobucket.com/albums/x407/idjitdragon/20141213_171637.jpg
 
Both are 500x500; 43 and 34kb respectively
 
 
Anyone have any idea what's going on here?
 
Cheers
 
Martin