When tom29739 at #wm-bot on freenode used @seen tom29739 , wm-bot returns "I have never seen tom29739" instead of "are you really looking for yourself?". He cannot @seen other users too, and it always return "I have never seen <nick>". tom29739 tried the @seen command on other channels, and it worked. He even restarted his IRC client, and still, no luck. Other users can use the @seen command, and it returns the right message.
UPDATE: Even when tom29739 is completely logged out with no cloak, etc. @seen still cannot be used.
UPDATE 2: tom29739 used webchat and tried @seen again, and now it works. It seems to be a problem with his IRC client and/or bouncer, which is HexChat and ZNC, respectively.
UPDATE 3: tom29739 used ZNC in Kiwi IRC, and it worked, so it is a problem with HexChat.