Failed Logins After Installing HideMyWP

I was getting notifications of many failed login attempts to my WordPress admin. In order to thwart the attackers, I installed HideMyWP and hid the admin area at a secret URL. Since doing that I am still receiving many failed login attempt notifications.

I don’t really believe that an attacker could have identified my secret admin URL path, because it is fairly complicated. How could I still be receiving these notifications?