Rakuten/Dell won't give me my 10% cash back for a monitor I ordered on Dell Outlet.

I just would like to know if I can contact someone who can explain to me why my AW 2723DF monitor I ordered from Dell Outlet a few months ago during a special 10% cashback promotion, didn't qualify for the cashback?

I've emailed Rakuten numerous times and this is their current reply to my email. 

"For this order, Dell Outlet has not verified this purchase was eligible for Cash Back through Rakuten. This means Rakuten has not been paid commission on this order, and the commission is what we use to add Cash Back to your account"
 
I don't understand since in the terms of service, there was no mention of "monitors" or "gaming monitors" not being disqualified for the cash back. I still have my receipt/order number to prove I purchased this device. 

I would also just like to know what does/doesn't qualify for future purchases as well considering there's another 10% Rakuten special going on right now, but I'm not going to buy something expecting 10% back when its this much of a struggle without any explanation what does/doesn't qualify. 

Thank you.