Are you sure the tags weren't written? If the mp3 files previously had v1 tags and you didn't delete them, then they are probably still there and will often show up first. The best way to save tag confusion is often to get rid of all the v1 tags first, then you will be able to see if the v2 tags are actually there easier.

(list 6284, Mk1 S/N 00299 4GB blue [for sale]. Mk2 S/N 080000094 26GB blue)
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(list 6284, Mk1 S/N 00299 4GB blue [sold]. Mk2 S/N 080000094 20GB blue)