I'm having the exact same issue.
1. Register the app.
2. Uninstall the app.
3. Re-install the app.
4. Now the app's registrationStatus on the client says unregistered, while I still see the application connection in the SCC.
5. Now calling unregisterApplication is ineffective.
I tried the solutions suggested here by Daniel, that didn't work too.
Any inputs on this would help.
