How can I successfully set up a webhook for order payments?

[jminardi]

I am trying to setup a webhook when a new order is paid for. I went to Settings > Notifications > Create webhook. I selected "order payment" as the event, and added this as the callback URL: https://jacks-macbook-pro.koi-vibe.ts.net/api/v1/shopify-order-webhook. That URL is running on my server listening to GET and POST requests. It returns a 200 response to either of those requests. When I manually get the URL with a browser the request is served properly. When I click the "send test notification" button nothing happens. I see no attempt to POST to the URL in my logs.

What do I need to do to get shopify to correctly hit this URL?