I had been using the GROUPING field in iTunes for format, source, year, country, genre and mood labels - with many smart playlists generated using this information. I use mp3tag to process mp3 files prior to importing them into iTunes, adding basic info to all tracks on an album in mp3tag and then detailed info to tracks individually inside iTunes whilst listening to the music. I just found out that any info added to the GROUPING field within iTunes 12.5 is no longer embedded in the mp3 file itself, but saved only in the iTunes library (not good). Apparently the new WORK field in iTunes is where I need to store the information previously held in the GROUPING field, to ensure that any data I enter in iTunes is written to the mp3 tag.
Would somebody please tell me how to create an ACTION that will copy all of the information currently saved in the GROUPING field into the WORK field in mp3tag. As far as I can see, they both link to the TIT1 field. Thanks