how it can be not filled if the actor is in world and I can see when I am ingame?
That means there's a reference to the actor in the world. It does not mean the
alias in your quest is filled. If your alias filltype is set to UniqueActor then you're probably ok (as long as that actor
is unique - having a second reference somewhere in the game will screw this up), if that is the only alias your quest has. But if you have another alias in your quest that is not being filled, your quest will not run, so none of the aliases will be applied.
the condition is just reach the X reference
NPC packages are not evaluated continuously, but at intervals (shorter if the player is near) - if you want to be forcegreeted the instant you reach the Xmarker you need to set up a trigger or script.
Forcegreeting is just like any other dialogue with an NPC, except that you don't start it by activating the NPC, they run up to you and it starts. Like couriers.