There are no rule settings in place that will trigger store credit for a specific order. For us, when customers use a discount code, the order only qualifies for store credit, not a full refund. The lack of this functionality is problematic as customers will always choose refund over credit. We will be searching for another return app to use.
Thank you for that feedback! Store credits in our app is unique from any other returns platform. We created them with best practices in mind and we realize there will be scenarios we haven't covered such as yours. We will absolutely put this into consideration for future development. Thanks again for the feedback and all the best to you!