You configure two seemingly compatible promotions, test the cart, and Shopify applies only one.
The real symptom
- An automatic discount disappears when a code is entered.
- Free shipping and a percentage discount will not stack.
- Both discounts are active but Shopify chooses one.
- Buy X Get Y conflicts with another promotion.
The likely cause
Multiple discounts combine only when the settings on both discounts allow the relevant combination and the discount classes themselves are compatible.
The confirmed Community fix
Community troubleshooting consistently starts by checking the Combinations settings on both discounts and then verifying that the cart independently satisfies each promotion.
Admin path
- Go to Discounts.
- Open Discount A and review Combinations.
- Save, then repeat for Discount B.
- Check minimum spend, quantity, product/collection, customer, and purchase-type rules.
Important limitation
Some same-product and Buy X Get Y combinations are more restrictive than order + shipping or product + shipping combinations. If Shopify cannot combine two eligible discounts, it can choose the better discount for the customer.