Target Delivery API - prefetch mbox content - just get 'state'

Hi, 

I am trying to use the delivery API to get mbox content, but the response does not contain the HTML of the mbox, just a 'state' value with a string.  Even using the exact example in the docs (http://developers.adobetarget.com/api/delivery-api/#tag/Delivery-API) in Postman, I don't get the response they show in the docs.

Documentation example request:
{
"id": {
"tntId": "abcdefghijkl00023.1_1"
},
"context": {
"channel": "web",
"address": {
"url": "http://demo.dev.tt-demo.com/demo/store/index.html"
},
"screen": {
"width": 1200,
"height": 1400
}
},
"prefetch": {
"mboxes": {
"name": "SummerOffer",
"index": 1
}
}
}

Example response:
{
"status": 200,
"requestId": "5efee0d8-3779-4b12-a74e-e04848faf191",
"client": "demo",
"id": {
"tntId": "abcdefghijkl00023.1_1"
},
"edgeHost": "mboxedge28.tt.omtrdc.net",
"prefetch": {
"mboxes": [
{
"index": 1,
"name": "SummerOffer",
"options": {
"content": "<p><b>Enjoy this 15% discount on your next purchase</b></p>",
"type": "html",
"eventToken": "GcvBXDhdJFNR9E9r1tgjfmqipf"
}
}
]
}
}

My response: