Stream URL missing in Email Notifications

I have two versions of Graylog running. OLD version 1.3.3 URL links in Email Notifications working well.
New install of version 3.1 no good, tried several combinations in Body templates with no success. Should I upgrade to 3.2 to resolve this?

Stream ID: {stream.id} Stream title: {stream.title}
Stream description: {stream.description} {if stream_url}Stream URL: {stream_url}{end}