Description tag/metadata

I don't know if this is an issue with this program or with iTunes, so I thought I'd start somewhere.

I have a bunch of audiobooks, both in mp3 and m4b format. I have this issue with both formats. Many of them have something in the "description" field when I look at the file in iTunes. When I bring the extended tags up for the same file in Mp3tag, the same description that I see in iTunes shows up there.

I can go and delete the "description" in Mp3tag, and it goes away. It doesn't show up anymore if I bring up the file in the program at a later time. But if I bring up the file in iTunes, the information in the "description" field is still there. I can't get it to go away unless I manually delete it within iTunes.

Am I doing something wrong? Is it possibly iTunes that is at fault instead? Thank you in advance for any help.

Yes. iTnes has a database of its own. What you see is the information stored in that database. You have to update the database.