No chest after S- on Veigar, haven't earned chest with him this season. Also lag before maintenance?

Long story short, I earned an S- on Veigar as support (went 7/0/7 in 19:57, honestly no idea how I didn't get S+ lol) and got no chest. The only things I could think of is that: 1.) You don't earn chests on S-, but on S or S+ (which I doubt is the case, I just looked it up because I thought it might be changed) 2.) The server maintenance that hasn't started yet, but acts like it has. (I say this because many players in my past 3 games have experienced heavy lag). Which, btw, why are we lagging? I thought it started at 6am PST, which is in 3 hours. [sg-shisa] me rn

Edit: Didn't have chests available for this week [sg-zephyr] me now