Why is the "Add product" button grayed out?
If you're trying to add a subscription product to an existing customer's subscription, the Add product button may appear grayed out. This happens when the product is set up with dynamic pricing only.
Products that use only dynamic pricing plans can’t be added as subscription items through the merchant portal. They can only be added as one-time purchases to existing subscriptions.
To avoid this, add a non-dynamic pricing plan to a product that is currently assigned a dynamic pricing plan. Be sure to set the product plan settings to not available on the subscription widget if you do not want the regular subscription plan to display on the storefront.
