I have some mp3 and i want to delete the discnumber value, but i cannot do it. I've tried with extended tags, one by one, trying also to remove duplicate TAGS, but the tag don't disappear and value always is there.
Even I've delete the tags with other programs, but when i read again with mp3tag, the tag is included.
The only way to remove it is deleting all the tags and then tag the tracks again.
Try it with:
Tools>Options>Tags>Mpeg and set the "Delete" Option to only APE.
Then load the file again and try Edit>Remove tag.
If the DISCNUMBER is still there, go to the Extended tags dialogue and delete the field there and see if it works.
If all this fails: check the file for consistency with MP3diags.