some variant is havan't color,e.g.3check,monster,xiangqi and breakthrough
bug on personal page
In some games it is an advantage to have a certain color, so in rated games the color cannot be selected.
im not mean to play white/black,i mean in personal page the line chart has no color.
If you only have a single point on the graph, a line will not get drawn. If you play more games with those variants and your rating changes you should hopefully see the lines you are referring to.