Hextech Chests not being given

My friend has not received a single chest even though he and I have gotten multiple S-'s to S+'s as a premade group.

I haven't had this problem until my most recent game as Taliyah where my friend gets an S- as Riven and neither of us received a chest even though he got an S and we have not received a chest from either champion this season. We DO OWN the champions that we played and neither of us understand what causes this bug, but it is frustrating.