I have tested this.
mp3tag supports tagging mkv now.
I tagged some things like Title and Artist in one of my test MKVs.
Then I placed this into my test library which uses only the Local Media Assets agent.
None of the tags was read and imported into Plex.
The only information that gets into Plex from MKV files are the tags on individual streams, like ‘Language’, ‘Title’ or ‘Forced’.
But that doesn’t matter for the matching process. These ‘Stream titles’ do only appear in the Plex Mediainfo and nowhere else:
Besides: @JuiceWSA I’ve seen that mp3tag does indeed write these ‘Global Tags’ now.
And it also has a way to erase them from the files. And this is way quicker than remuxing them in MKVtoolinx:
