I have a question...Did you tag the file with the art using the MMJB "Paste art from clipboard" function in the tagging dialog? That might explain the BMP format depending on where you got the art from. Try taking the same file and tagging it with a nice small JPG from a file...not the clipboard. See if that passes Emplode's check.

P.S. If you want, you can just remove the album art from your entire MP3 library using the tagging dialog. It'll take a while if you have lots of files, but it will work. That is what I did. I think I had about 150 tracks that wouldn't import originally, so I just selected the whole library, went to Edit Tag, then removed the art. No biggie, and everything imported just fine after that.