Hi,
Enable logging for webhook and see the logs for more information.

See:  Create a New Record Using Webhook in Odoo 17

Thanks

The automated action might be throwing an error. Add a try-except on the code and send another request. You should get an "ok" as response.

You can also test it with an empty automated action. In the webhook "Target Record" field, you can use: model.search([],limit=1)