We have an intermittent issue, and is the following scenario:
Customer has a coupon on the order and the discounts are applied correctly on the cart but when the order is submitted the coupon is dropped off the cart and the order ends up by having no discount.
What we found is that this happens just with coupons that used for a lot of users, coupons that are just for some users have never failed like this.
Does any of you have faced an scenario like this in the past?
Can you confirm whether it is happening only after you wait for sometime between Login and Submit Order? I have faced similar issues because of Profile expiration. Before Committing the order, it tries to validate whether the promotion associated with the coupon is in the activePromotions in Profile. Coupons are normally dropped if it is not there.