I'm a new user of mp3tag. And I was trying to add cover art for a film in mkv format with 12 chapters. I tried adding the cover art by selecting each chapter one by one. I also tried adding cover art by pressing Shift and selecting all at once. Both didn't work. What did I miss?
Another issue, I tried adding and saving a cover art to an mkv file. But it didn't get saved, no matter how many times I tried. Additionally, I right clicked the file and chose Extended Tags. There Add cover was greyed out.
Screenshot (As a new user I'm limited to one image per post, so here is the link from imgur): https://imgur.com/a/UhFuk