https://www.naeu.playblackdesert.com/en-US/Adventure
If I search any player family I know, it returns results a normal.
If I search myself, no results return.
My guildmates have confirmed that this is the case as well. A player is unable to search for themself.
Workaround: If you use a different browser or incognito mode, so that you are not logged into your own account, then you can search for your own family name.
It seems like unintended behavior to be unable to / prevented from search for your own family name while logged in.