Currently Being ModeratedMay 25, 2012 2:00 AM (in response to tawauna)
I guess I have successfully solved that. Somehow predicted this problem's appearance and added a function of ID3 tags version conversion. Just convert all of your mp3 files' tags to version 2.4. worked for me, now bitrate gets downgraded and artwork is safe.
p.s.: some of the artwork (especially files that originally were higher bitrate AAC converted to 128 kbit/s) won't show the artwork in the artist or album list at first. just play any of such songs and artwork will show up.
Currently Being ModeratedDec 11, 2012 8:28 PM (in response to Alexanderre)
You can also try using something like iFunBox to rename the file MediaLibrary.sqlitedb. Power your phone off and then back on and then resyc your phone with iTunes.