So there are rewards that are completely random. And then there is cash back which is exactly correct.
1st statement cashback correct . No reward
2nd statement correct cashback . Extra reward.
3rd statement no cashback yet . 3days delayed and reward. Reward is random. No clue how it's...
Eterna to Amazon wallet is 3.75% confirmed but you get charged 2.36% as Convenience fees
"Convenience fee of 2.36% (incl GST) applicable on Credit Cards"