I wonder if the increments are a cause in not triggering the credit. Wouldn't make sense though, hmm....
I did $50 increments on September 22nd and September 25th. They hit my CC on the 23rd and 26th respectively.
The first $50 credit hit on September 28th and the 2nd $50 credit hit on October 2nd. So about 5-6 days.
That is in line with my Netflix credit which took about 7 days for it to appear as a credit.