I enabled "Ignore unknown Usernames" in the Organisation->Settings->Login Behaviour and Security(there was the 'Saved Successfully' popup).
Yet, when I enter a wrong username, I still get "User not found in the system", just like when the setting was disabled.
I also set the same setting at the instance level ( Default Settings->Login Behaviour and Security). Then I clicked 'Reset to Instance Settings'-- still the same result.
Have I misunderstood how it's supposed to work, I need to do something else, or is there a problem?