I have used it before at Pecos Bills, so I wonder if that list is curent. I've found very few places Diwney operated that do not take it -- but having said that, I always make sure I have back up payment method handy: room card, cash, and credit card (which I use at S&D, which I agree with PPS does not take Rewards card.).
Computer system glitches do happen.
To get a better list, you might try emailing guest relations or Disney Visa.