Webhook not firing, but url endpoint is validated

Hello,

I was able to create an account-level Server-to-Server OAuth application to host our webhook events and API calls. The app shows that it is "Activated"

and it shows up under installed applications on our account:

Within the app, under "Features", I enabled "Event Subscriptions" to be able to utilize webhooks:

I checked the box to enable the webhook for user.status_changed:

The Endpoint URL validated successfully:

But when I test changing my status in Contact Center...

I do not receive any request fired to my webhook endpoint (which is configured to receive POST application/json, and tested when validating the endpoint).

Is there any additional configuration that needs to be done for it to fire? Or am I misunderstanding how it's supposed to work?

Thanks,

Steven