Hello Jonathan,
We would like to inform you that once you create a Coupon and assign it to a Plan or All Plans then our system freeze the changes so you can change only two things through the edit process, one is Date and another is Maximum Redemption. So, if you want to made more changes in the Coupon then we will suggest you to Create a new coupon instead of making changes in the existing coupon and make this coupon either Inactive or you can Delete this Coupon.
Hope the above information helps you.
If you need further support please reach out to us.
Regards,
Vipin Mishra