I don't know if this is a known bug, but I have had iTunes and/or Match rearrange by playlist 3 times already. I was uploading a song to iTunes Match and went to see my playlist to arrange the song where I wanted it and my whole playlist (800+ songs) was rearranged. It has happened since I got Match. Don't know if this is a bug, but maybe I am doing something wrong. Any info would be appreciated.