[CLIENT] Level 6 Mastery Token Popup shown when receiving S- or greater, no token rewarded

I played a game that got me to level 5 mastery on Jax. For that game I received an S-, prompting the popup for a level 6 champion mastery token. I didn't receive the mastery token, but I didn't expect to as I was level 4 during the game. The bug I'm reporting is not that the token wasn't received, but that the popup occurred even though it shouldn't have.