I'm seeing the same thing as Ardesjo, but I can add a little more information. You check out as usual, enter the discount coupon code, and go through PayPal Express. When you come back to the store, the coupon is missing. If you then select the "Edit" option next to Payment Method in the Billing Information box, repeat the exact same coupon code as before and select the same payment method, the discount then shows up on the Order Confirmation page.
The same is true if you empty the cart and go around again *without* exiting from the browser - make the same selection, use the same coupon and payment method, see the discount show up.
The same is also true if you select the "Check/Money Order" payment method instead of PayPal Express.
This suggests to me that it may be an initialization problem somewhere - perhaps something to do with session variables?? It seems like the discount only fails to show on the first purchase after going to the store. Subsequent purchases work OK.
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