Have Not Received A Chest While Getting S's Yet My Profile Says I Have 4 Available [GAMEPLAY]

Hello,

As I have played a recent ranked match with Xerath, being able to go 24/4/22, I received an S+ rank for the match. I did not receive a chest for the match yet after I finish the match I go to my profile and it says I have 4 chests available. When I put my cursor on the chest icon, it states: "Get an S- or higher by yourself or with your premade to earn chests." I haven't been paying attention to this issue much but it seems I haven't been given a chest, even though I have been obtaining S rated games for weeks. I would like some assistance on how to clarify and resolve this issue so I may be rewarded the chests that are promised. This has not been only occurring within ranked games but also normal games. I am not certain on whether this is a bug or not but any clarification would be greatly appreciated.

Thank you very much, MicrobioMajor