Budget: 40 USD Deadline: 1 day
The problem you are describing is related to the fact that when using the method $basketItem->setField("CUSTOM_PRICE", "Y") in Bitrix (I assume we are talking about the 1C-Bitrix platform), the standard logic for applying discounts and coupons may be reset, as you are manually setting a custom price. This behavior is typical for a system where changing the price directly conflicts with the discount mechanism.