Event Hook verifiaction fails

See below the error I get when trying to verify an event hook.

If I make a POST request to the event hook endpoint, via Postman, it works. Similarly, GET with the X-okta-verification-challenge works as well via Postman (3rd attachement). It works with curl too. Via Okta, it just doesn’t work. We’ve checked; the request doesn’t reach our service.

Call identical to that in Okta in Postman:

Successful call straight to the event hook endpoint:

In a previous post, I saw that the response should be encoded in utf8. With application/json it’s by default utf-8 and this page doesn’t indicate the response of the verification call the Okta backend makes needs to explicitly defined as utf-8:

https://okta.my.site.com/help/s/article/Unable-to-verify-event-hook-Hook-hook-name-execution-failed?language=en_US

It’s not the first event hook integration we make with an Okta org and our other orgs are fine with application/json being returned.

Is there a way you could tell me what the Okta backend is getting back for this failed call? It’s very hard to debug with a generic error message like this. I’ve been trying to figure this out for over a day…