I have customized the columns to include the %publishers% field and have added this field to the tag panel. However, the program doesn't save the information to the publishers field. I have even manually added the information through windows explorer and when I open the files in mp3tag the publishers field is blank.
If you want to be compatible with the Windows Explorer properties dialog, then you have to set Mp3tag to read and write the tag-type "ID3v2.3" ...
... provided that the explorer can work with the "ID3v2.3" tagfield TPUB, ...
which is named in Mp3tag as PUBLISHER.