Examples: higherman and thommehh on Pokerstars. This is not a mistype and they are not blocked. They just are not in the database. I asked Sharkscope support about this. Their reply:

"Players need to Opt In on this network, you can see further information regarding this in our FAQ and news sections. Please also see our Opt Out link for Opt Out information."

Together with FAQ:

"It is very rare to find a player that is not in the database. It most likely means the player has not played a real money tournament before or you mistyped player name."

Is quite confusing. I asked for further explanation, but received no reply. Maybe you can help me.