Graph Assets and Unity assets in general, can’t have references to scene objects. This is a Unity known limatation. It’s simply impossible 🙂
Bound Graphs exists exactly for that reason. To allow you to assign scene object references within the graph.
If you want to use Asset Graphs, the way to work with scene object references like game objects, would be to use Blackboard variables. Since the Blackboard is a component attached on the agent which is not an asset but in the scene, it CAN have references to other scene objects.
Gavalakis
