I found that secure notes category in Keychain Access are not synchronised between my Mac computers.
Solution: Copy of move a secure note to iCloud keychain.
Re: http://hints.macworld.com/article.php?story=20140303121648944
MacBook Air (13-inch Mid 2011), OS X El Capitan (10.11.6)
Another time I found that secure notes even in iCloud keychain stop synchronising between computers.
And I fixed it by Signing out my account of iCloud and then signing in back again. Synchronisation was restored.
Read carefully messages about copy of your documents and data when signing out.
You may inadvertently lose your data.
Unable to sync keychain secure notes
