If you use store rewards to pay for item for Fetch Rewards don’t be surprised that you get little to no points because they say the following:

Special Offers vary from shopper to shopper and are available for a limited time only. Offers for beer, wine, & spirits are void where prohibited by law. Points awarded are based on final price paid pre-tax and after all other coupons, discounts, savings, and retailer-specific currency (such as CVS ExtraBucks) are applied.