Your link to that post is a really nice example showing the source and how they work. He has done a nice job at that.
There you can see we are using trigger.to_state.context.parent_id is none (his example is trigger.to_state.context.parent_id == none)… so this is true for devices and user interface but not an automation. With you reaching out we now know scenes also fall into a none.
If we look at the other examples user_id would allow you to have scenes but you wont be able to control it through the device only the user interface. This is why I have used parent_id.
I must admit scenes are nice but I only recommend using them if you have all different light settings when you turn ON your lights. For automations they make it hard and is why I just use entities. You can use 2 turn on light actions and set different light data.
Now you can see the challenge. It would be nice if HA sees a scene as is not none.
Blacky 