I had a very similar problem to the first post to this thread, the thing is I've always used both Emodio and Samsung Media Studio. I don't know if this matters but I had American music on my p2 and using those programs ALWAYS worked out just fine to put on album art. Then recently today I got music from a foreign group.I used my Emodio program first to get the album art on it and it didn't work! Then I decided to uninstall and grab Samsung Media Studio that didn't work either!
So then I figured I changed the format of the images. The formats .jpg and .png did not work!(Also for .png for Emodio it was not a supported format. Oh for those using the same version of Emodio or Samsung Media Studio I do use the Korean version) Anyways I then resulted to change the format of the .jpg files (with paint) and resolve to .bmp! The quality is really bad but at the same time I didn't really care as long as the album art was on it. So my suggestion is to try and change to .bmp 24-bit if you want. Orrr try and uninstall it and redownload the latest Emodio on the internets. I was just so shocked that after trying both .jpeg and .png it didn't work and .bmp pulled through. So if all fails go with .bmp!
Okay that's all I had for suggestions enjoy and good luck!
Oh before people get angry. I have a Korean 5.10firmware and all of the above happened today.