I noted a difference in two .sgf files. One was a full game (downloaded from Gobase probably) and the other was downloaded from DGS. The first showed move numbers correctly; in the second all moves were displayed as '1'. On examining each file with a text editor I noticed that in the DGS file the first move had the property MN[1] included; it was a handicap game. After removing the MN property the numbering displays correctly. It seems that Go Suite does not interpret the MN[] property correctly.