I have installed the new Salesforce Lightning Inspector Chrome extension, which sounds pretty cool.

https://developer.salesforce.com/blogs/developer-relations/2016/02/introducing-salesforce-lightning-inspector.html

Unfortunately, when I try to inspect a Lightning app, I just get a blank "Component Tree" tab under the "Lightning" tab in Developer Tools.
Am I missing something?
I have tried this with a couple of simple apps that have one or two components in them. From the Force.com Developer Console, I open the app and click on the button to launch another browser window with the app url that runs under Aura. (The url ends in .app) Then I launch the Chrome Developer tools and click on the Lightning tab. The only thing displayed is a blank Component Tree tab.