Hey Steven,
I've checked your site and found that you have created discount coupon for each recurring type with 100 % discount.
It means when user apply this discount coupon then 100% discount applied for all the recurring payment , means 0 amount for all recurring payment.
PayPlans don't support 0 amount recurring payment , even if you can't set 0 amount for recurring type plan. It should be some greater then 0. That's why you are hitting this issue.
Is this a built in feature to stop $0.00 transactions or is there another setting I am missing?
In case of fixed payment , user will not redirect to payment page if amount is 0. In case of recurring it always redirect to payment page to create recurring profile creation to collect further payment.
So , if you want to apply 100% discount for first payment only then you should create Coupon Type to
Initial Purchase.
When user apply this coupon code then recurring plan will, be converted to Recurring + Trial , where trail will be free and further recurring payment will be done with regular amount. As paypal support Recurring + Trial plan , so you can use this discount type.
Update us with response and correct me if i misunderstood.
Thank you for understanding !