Your screenshot doesn't show a difference between mp3tag and MusicBee. It only compares MS Explorer and MB.
Also I fail to see the 'bug' you believe there is.
You might want to learn about 'mapping' to see if it solves your issue. There's a lot of info about mapping on the mp3tag forum.
If you can't explain what the assumed 'bug' is exactly, I will move this question to 'general' before late.