Amazon Selling Partner API /sales/v1/orderMetrics Only Returns Timestamp Instead of Order Metrics

Question

I'm working with the Amazon Selling Partner API, specifically trying to fetch order metrics using the /sales/v1/orderMetrics endpoint. I'm expecting to receive aggregated order metrics for a specified interval, but all I get in response is a timestamp. I've double-checked my request against the API documentation, but I can't seem to figure out why I'm not receiving the expected data.

Request Details:

    Endpoint: /sales/v1/orderMetrics
    Method: GET
    Parameters: marketplaceIds=ATVPDKIKX0DER (Amazon.com US marketplace)
                interval=2024-03-03T00:00:00-07:00--2024-03-09T00:00:00-07:00
                granularity=Total
                firstDayOfWeek=Monday

Expected Response: A JSON object containing aggregated sales and order metrics for the specified interval and marketplace, including metrics such as total orders, total units sold, and total sales.

Actual Response: {"timestamp": "2024-03-23T06:26:32.032Z"}