Hey Greg,
Okay, it looks like the way your template customize the modal behavior is affecting how PayPlans modal is working. The best way to fix this temporarily is to apply the css codes below into your template's css file.
[gist]
body.sunfw-com-payplans .modal-backdrop {
display: none;
}
body.sunfw-com-payplans .sunfw-section.sunfw_main_content {
z-index: 4;
}
[/gist]
These fixes are only applied on PayPlan pages but it is only a temporary fix until we revamp the structure of PayPlans. As of now, our priority is pushing out PayPlans 3.7 with a more simplified admin appearance.