Google Console - Cloud Datastore Query returning “

Question

In Google Console, I get

"Backend Error"

when trying the access Cloud Datastore administration screens (Dashboard & Query screens return "Backend Error". Index screen works, somehow).

When looking at my App Engine Logs, I see this in my default module logs:

404 - /datastore/v1beta2/RunQuery Error 404: The resource could not be found.

The same code in development, and deployed to another App Engine application works perfectly. Any idea what's going on?