You might try contacting the RIO's Reward department. I have emailed them a few times. They respond very quickly, sometimes same day.
Some of the cash back offers are bounce back promos. Otherwise, sure they give you back you loses up to "X" amount but you get the $$ on a future trip within a specified time.
Try logging into your HET Rewards account on the Harrah's website. Find the $750 offer in you list of TR Offers. When you click on it you usually can read "most" of the fine print details.
"When The Money Comes Out Of The ATM, Scream "I Won!, I Won!"