So, you aren't seeing them in that tab, right?
If you have access to your server logs, try looking at the access log. Another poster here in the forums pointed out that an easy way to tell if an ip was being blocked was to note the size of the file they received when they hit the wp-login.php page. There was a distinct size difference between a valid IP address and one that had been blocked, showing that the bad IP was being served the text page telling them they were blocked.
Can you try updating to the latest version and checking again, just to be sure?
Thanks!
tim