Keychain Secure Notes AWOL

Hi, yesterday I installed MacOS update (High Sierra). Today I went to access my Keychain Secure Notes only to find all of them absent. I've been researching how to restore them, all roads seem to lead to restore login.keychain from TimeMachine, but that isn't resulting in any solution. Needless to say, secure notes are used to store sensitive information not recorded elsewhere, so I am very keen to recover my notes. Help please!