Yes that is a blank user name in single quotes and no way to block it using the common names comma separated string. Tried using a double comma in the string but it was edited out. Login attempts are coming hot and heavy forcing me to shut down the site since I cannot access it or login to the back end. Below is an example email from an attempted login.
A user with IP address 188.8.131.52 has been locked out from the signing in or using the password recovery form for the following reason: Used an invalid username '' to try to sign in.
User IP: 184.108.40.206
User hostname: 220.127.116.11.cable.dyn.cableonline.com.mx
Any help blocking this is greatly appreciated.