I'm getting errors in several media players after adding any and all tags. I've used mp3tag successfully in the past. What's changed? See screenshot in link.
What kind of files are these? What was the source? Have you looked at these initial steps to try to resolve?
See also here:
I used a 3rd party tool to covert from YouTube.
I reviewed this thread and this seems almost my issue exactly. I’m going to try a different 3rd party converter and report back.