Promotions that should be restricted to a specific shipping method (SLA) are not behaving correctly unless the deprecated isSlaSelected flag is explicitly set to true. The new Regular Promotion UI no longer exposes this flag, and when creating promotions through it, the flag defaults to false. This results in incorrect behavior, where the benefit is applied to any available shipping method, as long as the specified method is listed among the options in the cart simulation.

Simulation

• Create a promotion with a discount restricted to a specific and valid shipping method using the new Regular Promotion form.
• In the cart, add a product and ensure that the specific shipping methods are available for the cart.
• Noticed that even if the selected Shipping Method is not the one configured in the promotion settings, the discount will still apply
• The expected behavior is that the discount should only apply if the specific shipping method is actually selected.
• This only works correctly if the deprecated isSlaSelected flag is set to true (which is not possible through the new UI).

Workaround

Set isSlaSelected = true via API. This ensures that the promotion is only applied after the matching SLA is selected.