No, the cash back is like this (purchase1->purchase2->purchase3->purchase4 (rebate on 4th purchase))

@gkar45 if you look at the account history for a cashback you will see that it is as @Ophoster says. My latest purchases went

Purchase card 1
... Notification that the card is being added
... Notification that the card has been added to my collection
Purchase card 2
... Notification that the card is being added
... Notification that the card has been added to my collection
Purchase card 3
... Notification that the card is being added
... Notification that the card has been added to my collection
Purchase card 4
... Notification that the card is being added
... Notification of cashback
... Notification that the card has been added to my collection
... Notification that the cashback has been paid
Purchase card 5
... Notification that the card is being added
... Notification that the card has been added to my collection

Only the lines in bold appear in the account history. It is not clear why we get two notifications about the cashback - the first is an "information" category message the second is tagged with the "earned" category. I interpret the first as a message that the cashback will be paid, the second that it has been paid but the wording is ambiguous.

It strikes me that a conceptually simple improvement would be to include the actual balance (as recorded by the server) with each of the account history messages as that should make it clearer what is going on whenever there is a dispute. However, conceptually simple changes are not always simple to implement.

@TheEmu
this would be a very useful innovation
Might also be good when You refill your credits, added 100, 500, 600 whatever at new balance is: ...

I'm pretty sure I did not receive credit for my fourth card, either. It shows in my account history as being paid, but I was watching the credit counter, and it did not go up. Re-syncing did not help.

I agree with @TheEmu that showing the account balance in the account history would be very useful.

I'm pretty sure I did not receive credit for my fourth card, either. It shows in my account history as being paid, but I was watching the credit counter, and it did not go up. Re-syncing did not help.

Your credit doesn't change when you select the 4th card. At all. Presumably you need the required number of credits before you can initiate the purchase, but that little (or big) green number at the top of your screen will stay the same throughout the transaction

It worked fine on the second series of four cards. Maybe an intermittent problem.