I am just starting to learn SpriteKit and I'm having trouble selecting a scene to preview an action in the actions editor. I created a new macOS Game project (Language: Swift, Game Technology: SpriteKit). When I open the generated 'Actions.sks' file, I see the message "No Preview Scene Selected" in the editor. I see the 'GameScene.sks' scene listed in the "Select..." control in the lower right, but it is greyed out. I'm not able to figure out how to select a scene to preview the action. I'm running Xcode 26.2 on macOS 15. Thanks very much for the help.