As of today I\'m unable to Query my own Datastore from the new App Engine Admin console. I\'m stopped by an Datastore Error \"You are not authorized to use Google Cloud Data
Looks like it's been resolved as of Today. I'm now able to access the Datastore Query page.
I had the same problem (reported and fixed) few months ago, I guess it came back with the last admin console update last week.
It is not a decent workaround but if you really need to perform a query before they fixe the issue you can: