Hey @Verlence,
Welcome to the Klaviyo Community!
Just making sure we have all our bases covered here, since you’re using custom uploaded coupons, have you made sure to also upload them to your Shopify backend to be recognized? From my experience, when using custom uploaded coupons, users often times miss this important step of uploading the same coupons to their ecommerce platform’s backend for the codes to be recognized when used. If the custom codes are not uploaded to the ecommerce backend and only to Klaviyo, it’s expected behavior that the unique codes that were uploaded and distributed from Klaviyo would not recognized when used.
I was also curious as to the use case pertaining to your custom uploaded coupons as well since it seems like you’re currently using Shopify - which supports unique coupon generations within Klaviyo natively. Because Klaviyo natively supports unique coupon generations, you typically wouldn’t need to go through the steps of manually generating coupon codes and manually importing them to Klaviyo for use. Instead you should be able to simply create the coupon within Klaviyo which would also automatically be recognized within your Shopify’s backend.
It may also help to take a look at some of our Help Center resources that I’ve included below to learn more about coupon codes function within Klaviyo:
I hope this helps!
David