Do any of you have this problem tagging MP3 art?

I have some mp3s that don't want to keep tagged artwork no matter what I do. I use mp3tag to embed the art.
I'll do it on my desktop and move a copy to my laptop. I load up Traktor and the artwork is gone. I play it in WMP and the artwork is gone. Some I have done this several times. I see it working on the desktop but no longer working when I move a copy to another computer. The problem seems to work in reverse as well.

Any ideas?

Did you press save when replacing the artwork in mp3tag? It is not saved automatically.

Yes of course I save. Ha ha.

do all your other tags save correctly?

So I had this odd theory that programs could but disliking album art size or something i read about there being different ID tag versions maybe?