I second this. I guess that instead of player character you need actual pointer to Target_BP actor.
Also you are using dispatchers in the opposite direction. They are best for situations when one needs to tel many that something happened.
Not when many actors may tell single actor that event happened.
For communication from multiple blueprints to player character you simply make event in player character, then trigger that event from Target_BP.
Also if you are not sure what class your target is use blueprint interfaces,