OS X drag and drop album art: I'm not able to save the file

I was able to reproduce it with Firefox (I was also using Safari) and will work on supporting the pasteboard format used by Firefox during drag and drop.

Thanks for pointing! If you happen to use Firefox again, you can also right-click on any image, copy, and paste via right-click on the cover window in Mp3tag.

If you can identify any common pattern, e.g., as @MotleyG pointed out, it would be very helpful to know. A fellow community member had similar issues with WAV files and identified this workaround: