AI Line of Sight check doesn't find Client Player

I have a service in the enemy behaviour tree that checks if the enemy is currently seeing the player. On the server, the enemy does detect the player and acts accordingly.
If the enemy wants to detect a client player, nothing happens. I can see the line being fired on the server, but the enemy does not see the client player nor react to him. The server even prints the corrent player actor when I use the print string node with the actor connected, but the AI does not react at all.
I thought all services would be replicated over the network and it should not matter if the enemy detects a server or client player. But why does the enemy not see the client player, only the server player?