Publisher tag not embedded properly

Hi.
I'm editing tags for my audiobooks (.m4b) and everything works flawlessly except for the Publisher tag.

I added a new column and choose field & value %publisher% for it (the %publisher% field is an already available extended field in Mp3tag). I added the values for my audiobooks and hit Save.

When I right click on the file and hit Properties, as well as when I load my audiobooks into an audiobook player, the Publisher field is empty.

I check the file with MediaInfo, the tag is registered as pub when everything else I need works just fine and shows as proper values (Title, Subtitle, Artist, etc.)

Is there any reason for this and how to get it to work properly? Also can we have extended fields for language and author as well? Thank you.

P/s: This is irrelevant but now I see that most ID3 tag reader register audiobook narrator as composer, while author is registered as artist and performer. Shouldn't it be the other way around? Is there anyway I can change this?

See e.g. here:

see the FAQs:

Thank you for your reply.

  1. I checked the thread you linked but it seems to be a question from @VortX that they themselves haven't found the answer?

  2. You misunderstood my question. I know how to use Action two swap values of two fields and I wasn't asking about that.
    My question was: Now the tag reader is reading artist as author and composer as narrator. Then it shows kinda funny in the tag list: Performer: [author name]; Composer: [narrator name].
    Isn't the author the one "composed" the book and the narrator the one "performed" the book? Now it gets all mixed up.
    I understand that because the book gets "attached" to the author, it's their property, so they get the artist field, but the performer and the composer fields don't make much sense, it just bugs me.

So, what do you think MP3tag can do about the implementation of your player except move field contents from one field to another one?
If that was a feature question about the player, I would think that such a question would best be asked in the support for the player.
And once you found out how it should be, MP3tag will probably help you to get the right contents in the correct fields.

That was just a side question tagged along because it was bugging my mind. I just thought maybe someone would know, we don't have to focus on that.

In MP4 files like your .m4b, Mp3tag stores PUBLISHER information in the ©pub box. This may not be supported by your playback software, which might expect it as part of the XML in ITUNMOVI.

The documentation for MediaInfo is lacking details for its MP4 tag support. Its source code repository has no file dedicated to it in the folder one would expect to find it in – they are handled elsewhere. Alas, it’s indeed lacking support for this particular field.