Masteries changing automatically when game loads in on Braum to previously used page

In two separate games tonight as Braum in the new ranked dynamic que as support, I double checked my runes and masteries before locking in, etc and before the game start countdown began. They were set to my Tank Support runes and My Braum/Tahm page of masteries for 0/12/18 (which has now been renamed to Tank support again to make sure I cannot even come close to "mistaking" them in case it continues). Upon loading into the game, my masteries had been changed to my "Fiora" titled masteries page of 0/18/12. I only noticed this because as I bought pots they were not biscuits, and definitely had Thunderlords as a keystone. This is a definitely a bug, maybe just isolated to braum as a champion and those masteries.