MP4 files with chapters ignore all standard tags; create “ghost tags”

[Florian]

@obskyr

Nero copies are created for every standard metadata tag that's set in that file, meaning that if the standard tags are changed with another program, Mp3tag cannot see the change, and the unchanged tags remain in the file as “ghost tags”.

I've adjusted this with Mp3tag v3.31b, so that in case a Nero tag needs to be written, it's now using a minimal version without duplicating other metadata.