Hextech chest not earned on champions in ARAM

I've already had S- or higher on Vi and Xin Xhao in ARAM but in that time I did not have any chests available, a couple of days ago and today I got S on both Vi and Xin but I didnt not receive a chest, although I did NOT have a chest earned by both of them this season, because I do have a list and a screenshot for the champs I've already gotten chests with so I know in ARAM champ select if I should reroll or not. So weirdly enough, I didnt get a chest but after I got the S, in my collection, it said I acquired a chest with them. When it happened with Xin, I thought I made a mistake, but now im pretty sure it's a bug. Did anyone notice such bug, or can any of the admins help me find out what went wrong? It wouldve been an easy case if I could see when I acquired the chest for the champ, then I could tell if it got marked immediately.