Fulfillment API returning blank response

[irook]

I'm having problems creating a very simple post to fulfill and close an order using this example:

https://shopify.dev/api/admin/rest/reference/shipping-and-fulfillment/fulfillment#create-2021-07

POST /admin/api/2021-07/orders/450789469/fulfillments.json

{
  "fulfillment": {
    "location_id": 487838322,
    "tracking_number": "123456789",
    "tracking_urls": [
      "https://shipping.xyz/track.php?num=123456789",
      "https://anothershipper.corp/track.php?code=abc"
    ],
    "notify_customer": true
  }
}

I get a blank (200) response.  I tried to simplify the post to:

{ "fulfillment": { "location_id": 487838322 } } 

Still blank response. 

I've tried using every different location_id on the account, but each simply gives the same blank response.

I tested my authentically successfully by adding a  note to an order, but I am having problems with creating a fulfillment.

Has anyone had this issue?

[GrahamS]

Hello @irook ,

Can I ask you to grab the x-request-id from your response headers and forward it my way? I'll take a look at the internal data to see what might be happening here.

Best,

Graham