I've noticed the plugin sometimes fails to authenticate the user.
I tried going into admin and the plugin settings. I tried the test tool and the login failed. I then clicked the server tab, clicked back to the test tool and ran it again, this time with a successful authentication.
My settings are obviously correct as they haven't changed between the two tests. Its also not a typo on the test tool user details, as the details I entered on the failed attempt as retained on the successful attempt - they haven't been re-entered.
Does anyone else have this problem or know what is causing it?