My Champion Mastery Grade in Post-Game Lobby isn't loading.

It's not really a big bug but around 50% of the time, my "grade" (S, A, B, C, D) that the Champion Mastery system gives me doesn't load up and there is just a blue, spinning, loading circle there instead. It seems to only happen on the Mac Client as well.

Is there a way to fix this problem or check your grade you got that game some other way? Any help would be appreciated! ^_^