No performance grade showed after match

I noticed that in the past week, I often don't get any performance grade. The post game lobby doesn't show it: it keeps loading and loading, but it doesn't give a grade at all. I tried to check the match history, but they aren't showed there too.

Now, this isn't a game changing bug, but I was really trying to get S for boxes and mastery tokens, but I can't receive them due to this issue