The reason why you are facing this issue is because of the number of items you are trying to purchase at once. The following redemption limits apply to Member Offers per product, per transaction:
Wine - 60 bottles
Spirits - 3 bottles
Cider/Beer/Non-Liquor - 3 packs
Premix - 4 packs
That means if you are trying to purchase more than the redemption limit at once, the price will change. These limits are to ensure that there is enough stock for everyone for these offers.
Last Updated: 22nd July 2020