It does appear to be networking related - the initial application loading takes a long time, and there is an error that "Connection timed out. Unable to connect to world" after the resources loading screen when opening a local world. Turning off networking allows me to open the world. Re-enabling networking causes the symptoms to appear again. Network performance is fine in other applications (e.g. Safari browser). Also tried signing out/in to xbox live, no change in behavior.
It does appear to be networking related - the initial application loading takes a long time, and there is an error that "Connection timed out. Unable to connect to world" after the resources loading screen when opening a local world. Turning off networking allows me to open the world. Re-enabling networking causes the symptoms to appear again. Network performance is fine in other applications (e.g. Safari browser). Also tried signing out/in to xbox live, no change in behavior.