I have created a Webhook, ChatGPT, and Twilio scenario that will receive a webhook from Twilio with a prompt, process a response, and then send it back to the user on WhatsApp.
I made a test run, and the scenario ran successfully, but the user didn’t get the message on WhatsApp. The module says it was sent successfully.
I will say this needs a deeper investigation.
Here you may need to use dev tool, (refer the link and you will get the idea on how to use it) and the see the request made from Twillio and also the success code and response receivedfrom their side to know what exactly happened.
Hope this at least point you in the right direction.