Mastery A+ and S+ = Mastery undefined

Hey Riot! Everytime, i mean EVERYTIME, i should have got an A+ or S my Mastery says "Mastery undefined". But not like this, when i get a C, B or A-. This bug occours for several WEEKS now! I am getting sick of this shit. I cant get any Chests, because i am not able to get a S Voting. So please fix this. I am okay with some days working for a solution, but not several weeks.
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