Not receiving chests anymore?

Just last game i was playing thresh and i got an S- yet i recieved no chest even though i havent gotten a chest for thresh yet, and i own him. Is there some sort of rework going on for chests or did they bump it up to have to be an S or S+ now? had the same issue where i got an S- for Ashe a few days ago yet never received my chest even though i hadnt gotten an S- or better with her previously and i owned her. couldn't find anything in patch notes or recent videos which is what confuses me... edit: it seems i have 0 chests available even though ive gotten only 1 chest in total this season. isnt it supposed to be 4 available per reset?