Webhook resource node empty

[dpbdpb]

I receive webhooks for INVOICING.INVOICE.PAID events. Unfortunately the resource node is empty, so I am missing the invoice data.

When testing with the Webhook Simulator, I receive the data in the resource node. How can I get this working for our live data?

Example:

{
    "id": "WH-5UU56563U68091820-72F22765U3536190K",
    "create_time": "2018-03-05T09:40:14.887Z",
    "resource_type": "invoices",
    "event_type": "INVOICING.INVOICE.PAID",
    "summary": "An invoice has been paid",
    "resource": {

    }
}