Champion mastery bugged

Earlier tonight I got mastert level 5 with Ezreal, with the whole full screen banner bla bla etc.

"Cool", I thought, now I can get the reward for that mission "Reach Mastery Level 5 with any champion", but when I got to the Missions screen that mission was labeled as incomplete. "Strange", I thought, "Maybe I only got mastery level 4 or sumpfin?".

Checked my collection, ordered my champions according to mastery level... "Where is Ezreal?" He is my most played champion, even more so than my penta killing Darius I whip out from time to time just to put a face to the album"Vulgar display of Power", by Pantera.

I found Ezreal at the bottom, when ordering the champions by mastery level. Checked my most played champions through my profile, Ezreal has 0 Champion Score! wtf? WTF?! 0 Win Rate, wtf?

It seems that when I passed the mark for Mastery Level 5 with Ezreal, his score got reset instead of giving him the Level 5 Mastery. Not fun. :(