I used the same model's and configuration as used in the tutorial on a fresh install of community 3.2
My problem is that when I go to edit the custom metadata and hit save, I get an error that says "Failed to update metadata". There is no log entry to point me in any direction when I try to update metadata.
The error handling should obviously be improved in the edit metadata page, but in the meantime to see the error that got returned install and enable Firebug and attempt the save operation again. In the Console tab of Firebug you will see the POST request and response, the response should show you the error.