User “test” multiple attempts – blocked but not in Blocked IPs

I am the only user and admin of a site and of course don’t use “admin” or “administrator” as login names. For about two/three weeks I’ve had irregular messages to say someone is locked out, that come from different countries & IPs each time (as these often do).
These seem unusual as the attempts are fairly random – not the short but intense hammering away that I usually see, but for example today at 13:48, 13:00, 10:53, 06:49 and 04:35.
The username tried in each case is “test”. There is no user account called “test”. After a couple of days I added this username to the “Immediately block” list and set a 60 day lockout period, with attempts counted over 1 day. But the user isn’t being blocked and the attempts don’t appear on the Blocked IPs tab on the Blocking page.
I’m puzzled – why does the lockout not appear to be working?