Update on things! We narrowed down the issue to be a specific WooCommerce NMI gateway plugin. When that payment method was active, it broke ALL payment methods listed in that “Order-Pay” checkout page. We switched to an alternative payment gateway plugin and things are all working properly. I’m assuming the issue began when WooCommerce was last updated a few weeks ago.
I appreciate the help and information. Creating a Staged site allowed us to test things quickly without affecting our high volume live ecommerce sites.