If the Killer Sudoku Advanced noted feature has stopped working, follow these specific steps to troubleshoot and resolve the issue:

1. Restart the Application: Close the Killer Sudoku app completely and then reopen it. This simple step often resolves temporary glitches.

2. Check for Updates: Ensure you have the latest version of the Killer Sudoku app. Go to the App Store, search for the app, and see if an update is available. If so, download and install it.

3. Reboot Your Device: Sometimes, restarting your device can fix application issues. Shut down your Mac and then turn it back on.

4. Reinstall the App: If the problem persists, you may need to uninstall and reinstall the app. Here’s how:
- Click and hold the app icon until it jiggles.
- Click the 'X' to delete it.
- Go to the App Store, search for Killer Sudoku, and reinstall it.

5. Check for App Permissions: Ensure that the app has all necessary permissions to function correctly. Go to your Mac's System Preferences, then Security & Privacy, and ensure that the Killer Sudoku app is allowed to run.

6. Consult Support or Community Forums: If the above steps do not resolve the issue, consider checking forums or community discussions such as Reddit or dedicated Sudoku forums. Other users may have experienced similar issues and could offer solutions. For example, users have mentioned switching to different applications if problems persist - learn more - learn more - learn more.

By following these steps, you should be able to restore functionality to the Killer Sudoku Advanced noted feature. If problems continue, contacting the app's support team directly may be necessary for more specialized assistance.