Webhook Missing Certificate

Hi, we are currently trying to implement webhooks as part of flow to update approved quotations in our system. We've run into issues with the setting to allow 2-way ssl which does not appear to return any certificate in a typical location in our C# Backend Application. httprequest.connection.clientcertificate is not populated and there is nothing immediately obvious in the headers. We also tried not returning the same cert in our response and Adobe accepted our response rather than failing on initial creation.

Is there a particular location this SSL cert should be present or anything I might be missing, such as an invalid pfx with no error?