Symptoms

Service Status Subscription widget not visible on service portal when the user previews a page after adding it.

Release

All the available releases.

Cause

The user will have to select one of the services to view the widget. This is why when someone previews the page there are no services selected to view the status.

Resolution

If you go to the following page and select any of the services to view the status, you can see that the widget is visible and  can be used to subscribe to the updates. 
https://<instance-name>.service-now.com/<portal-name>?id=service_status