Hello,
using RC 1.1.1 with
$config['log_session'] = true;
$config['log_logins'] = true;
$config['debug_level'] = 2;
$config['log_driver'] = 'file';
The unsuccessful logins are not logged in any of the log files while the successfull are.
I've also noticed that in the index.php file (in the root), you call the deprecated function (if it's deprecated) rcmail_log_login() instead of calling
$RCMAIL->log_login();
I've tested a patch and add in the else section (if the login fail) the code:
$RCMAIL->log_login($auth['user'], true, $error_code);
$error_message = $error_labels[$error_code] ? $error_labels[$error_code] : 'loginfailed';
$RCMAIL->log_login($auth['user'], true, $error_code);
$OUTPUT->show_message($error_message, 'warning');
And after this change, the log error message appears as expected.