Webhook is created, but callback is never hit - webhooks

Question

I'm trying to remove the pooling and integrate webhooks in the process of file conversion. The problem is that the webhook is created but the callback is never called back.
I'm following the instructions from here: https://forge.autodesk.com/en/docs/webhooks/v1/tutorials/create-a-hook-model-derivative/
The web server is started by the following command : ngrok http host-header=rewrite https://localhost:44366
The callback is http://f36a47b8.ngrok.io/derivative and is up and running. Post requests from postman(internal network) and Post requests from external networks (cellular data) are reaching the endpoint and are successfully redirected.
A hook is created:
"hookId": "51897b50-522a-11ea-b885-f34f23e3435e",
"tenant": "c0761189-32dd-4ca3-9e52-3ae400f91651",
"callbackUrl": "http://f36a47b8.ngrok.io/derivative",
"createdBy": "HUpqLPysSUmbFGlhQo0uG8XMqimfQnRG",
"event": "extraction.updated",
"createdDate": "2020-02-18T08:40:29.829+0000",
"system": "derivative",
"creatorType": "Application",
"status": "active",
"scope": {
"workflow": "c0761189-32dd-4ca3-9e52-3ae400f91651"
},
"urn": "urn:adsk.webhooks:events.hook:51897b50-522a-11ea-b885-f34f23e3435e",
"__self__": "/systems/derivative/events/extraction.updated/hooks/51897b50-522a-11ea-b885-f34f23e3435e"
}
Than a call to modelderivative/v2/designdata/job is issued with the following content:
var job = new JobRequest
{
Input = new Input
{
Urn = urnBase64,
},
Output = new Output
{
Formats = new List<Format>
{
new Format
{
Type = "svf",
Views = new List<string> { "2d", "3d" }
}
},
Destination = new Destination { Region = "EMEA" }
},
Misc = new Misc
{
Workflow = workflowId
}
};
The response is success with an urn (like before);
And from that point nothing follows from the webhook. The callback is never reached, even though that within some time the file is converted and it can be loaded in the viewer as before.
I've viewed those topics:
Unable to receive Forge webhooks, or unable to get them to fire
Why is webhook workflow not taken into consideration when creating modelderivative job?
but they didn't helped.
What am i missing ?

Answer 1

It turns out that there is a problem with jobs for derivative API in 'EMEA' region where no callbacks are called when a job finishes. Changing the region to 'us' fixes the issue and callback is hit when a job event occurs.
From the documentation example change the region parameter:
curl -X 'POST' \
-H 'Content-Type: application/json; charset=utf-8' \
-H 'Authorization: Bearer PtnrvrtSRpWwUi3407QhgvqdUVKL' \
-H 'x-ads-force: false' -v 'https://developer.api.autodesk.com/modelderivative/v2/designdata/job' \
-d
'{
"input": {
"urn": "dXJuOmFkc2sub2JqZWN0czpvcy5vYmplY3Q6bW9kZWxkZXJpdmF0aXZlL0E1LnppcA",
"compressedUrn": true,
"rootFilename": "A5.iam"
},
"output": {
"destination": {
"region": "us" <- Change the region form 'EMEA' to 'us'
},
"formats": [
{
"type": "svf",
"views": [
"2d",
"3d"
]
}
]
}
}'