I'm creating an infinite scrolling game where the player has to dodge incoming obstacles. I made the obstacles prefabs that will be instantiated accordingly. While I am editing the scene (dragging the prefab onto the scene), I can see it in both "Scene" and "Game" windows. The moment i click "Play", the prefab disappears. I've checked that it is on the right layer and right order. It has a "Box Collider 2D" but not a "Rigid Body 2D" so it doesn't fall out of view. It is not a child object. I would like to ask for advice on what could possibly be the problem.