I have been working on this for some time. I have tried a variety of tools, to no avail.
I am trying to edit the metadata in some mkv files I have. I do the standard media information, edit the tag, save it. If I do not close VLC 4.x, it stays and everything is grand. But, if I close VLC and reload the same mkv files, the metadata is reset back to what it was before.
I want to use VLC as that is my player of choice and it should work. This seems to be a possible bug for many years?