Azure Websites Deployment Slot Routing with ChangeDecisionCallbackUrl

I am trying to get dynamic routing working for Azure Websites. I can see the following article:

http://ift.tt/1LphCgC

This suggests using the "Testing in Production "TiP" callback functionality by setting the "ChangeDecisionCallbackUrl" property of the routing rule.

However, when I attempt to set this via PowerShell and then retrieve the value set, I cant see the url being set?

Therefore, I cant test the TiP extension is firing to do the dynamic routing I want.

Finding other instances where this is used is proving difficult...