It is on our to do list and it will be implemented soon.
You should use Replace Tags Options [CTRL+R] from Tools menu. Note you need to change combox box to Tag Version ID3v2.
Just select files that you wish to add a new genre and press CTRL+R
Hello, I recently had trouble using various genres that are not in the list(KARAOKE, MARIACHI, RANCHERA, GRUPERA, SIERREÑA), and this causes me problems since I have to use them in more than 50,000 files.
