No delay. I saved each item to my watch list beforehand then started the process from logging into cashrewards. The item in question was the 2nd item i added to shopping cart when i was going through the process.
It's totally weird imo given how it's supposed to work. A number of users on ozbargain have also experienced their higher priced purchase didnt get cash back. Which has lead some people to believe something dodgy is going on.