Google Cloud Logging contains the logs connected to API requests and responses to your DialogFlow ES agent. The logs will help you troubleshoot issues connected to your integration. The
guide itself is explanatory to see the logs, but here are the steps: 1) go to agent settings (general) 2) Click on Project (ID) 3) Go to Cloud Logging
As you are using Webhooks, I will suggest looking into the
error response which will allow you to pinpoint the reason for Instagram not being able to display the post-back response. I will also advise to look into this
developer resource that may help you infer more information from your endpoint responses.