In version 3.10.0 I am unable to change the text for the tag “TV Episode” or “TV Episode Number” in a mp4 file. The text is accepted, but when you click off the file and back on again it hasn’t change.
Sorry, I introduced a bug in the MP4 support with version 3.10.0. A fixed version 3.10.1 will be released next Friday, July 24. If you need a fix now, you can use the latest snapshot release from the development folder or enable the Mp4v2Metadata plugin, so that the TaglibMetadata plugin is not used for MP4.