Hextech Issues...

Hello there citizens of the rift! I recently had a Jax game where I managed to get an s-, and I got no chest. I double checked to see if I had got a chest already on Jax, but I hadn't since the season refresh. I was wondering if this was a bug or something I'm missing, and it would be really helpful if someone could tell me what the problem is. Thanks! [vlad-salute]