Hey there, welcome to the Metin2.SG forum, here you can find a lot of interesting stuff, why don't you register your account? It only takes a minute! Click on the "Forum Login or forum-register" button on the top-left corner!
He is not invisibile, you simply did not log properly, the maps and the other objects may be loaded but you are obviously offline. Is either because of weak network or you have ipv6 type connection which doesn't work on Metin2. Change to ipv4.