Problem with 4-Star Featured rewards for Beginner's Bracket

PhantomKing

I started the game nearly a month ago and since I am in the beginner's bracket, I have been taking the opportunity to grind arenas. The rewards have been paying off fine until I started trying for the 4-star featured for the first time with Electro. On the first round, I only scored ~400k points and that puts me some where in the high 90s ranked, and I got the 31-60% rewards as the result. On the second round, I pushed much harder and even spent some units on recharge, which got me to 1 mil points. I really had some confidence that even if I don't end up with the top rewards, I'd get something higher. But the result came out today, after more than doubling my score the first round, I ended up ranking 74 in the overall leaderboard, but for some reason I still only got the exact same rewards of 31-60%... I understand that the top rank rewards is for rank 1-50, and with that 23 spots in between me and that, how in the world did I not get either 1-10% or even just 11-30% rewards?