I feel like there must be a simple solution here and I am doing something very wrong but I can figure it out!
I am using an external hard-drive and mediamonkey. I export a playlist as an .m3u and then load the playlist to mp3tag. All of the files come up fine and I can see all of the tags including comment, which is what I want to change. I highlight all the files and then on the left side it changes all of the values to which is good. I add my behind the tag in the comment section so it now reads " wedding". I save the files and it says that it is saving (I see the little status bar) and then it says it's all done. I go to check the file in Mediamonkey or just by opening the file and viewing the info and the tag "wedding" has NOT been added. If I right click and open the individual file in Mp3tag the comment column shows " wedding"