[CLIENT] ? No chest after S rank!

Today I played with a champ after a long time (Taliyah) in Normal blind pick and got an S rank. After the match, I expected to earn a chest, as I had a chest available and this was the first time I ever played Taliyah in the season. However, nothing happened. I also checked my Collection and Taliyah is still shown as I haven't played her at all (best rank: N/A). She happens to be in the free rotation these days as well. I own the champion of course. This must be a bug. Is there a way to fix that and get that chest?