I've just released Mp3tag v3.18 and wanted to outline some of the new features:
You can now configure custom list values per field on the Tag Panel. It allows, e.g., for defining a list of composer names to ensure consistent naming. Or a list of country names or languages if you're storing those. It's still possible to see the values of the selected files if you prefer that, but an empty field on the Tag Panel now always offers the custom values (if set) from the drop-down list.
This new information field is set to
1 if the ID3v2 tag of the file contains any of the ID3v2 frames not supported by Mp3tag, e.g.,
SYLT. You can remove those frames by cutting the tag via Ctrl+X and pasting it back via Ctrl+V.
Please note, if you're using the Library feature, you'd either need to force-reload the tags of the files via File → Read Tag or Ctrl+T or start with a fresh library to see the newly added field.
As always, thank you for reading, your interest and your support.
Enjoy and take care