I think the rewards problem has something to do with the way the game perceives the "completeness" of the level. Remember a bit back we had a gauntlet event that required us to "Clear" a level to earn rewards? When people cleared the first level of SSS many received no rewards because SSS wasnt "finished"
I think these rewards issues are similar. For the last 3 or 4 gauntlets I have cleared all of the first SSS and I got the correct rewards. Before that, I made it into SSS but not all the way through and I got the wrong rewards.
Im guessing because you completely cleared the AAA tier, it registered correctly. It would be interesting for others to track this and see if it holds true.