Hi, I’ve taken a look at your site, and I can confirm that the 15% discount isn’t visible in the checkout.
(BTW, you should unsubscribe “testing@gmail.com” from your mailing list, as that’s the email I used to test the popup).
Can you give some more details on how the actual discount is implemented? For example, does your theme automatically apply a discount code, or does it use an automatic discount?
How does your theme apply the discount? Does it store data in the session, check the user’s email at checkout time, etc.?
If you can provide some information, that will help me isolate the cause of your issue.
Best,
Tobe