Rigidbody gameobject falls through plane

I have a rigidbody gameobject that has a box collider. The object is supposed to fly straight over the plane but when I run the scene the object just falls through the plane. The plane has a mesh collider with convex turned on but the object still falls through the plane. Any ideas why this is happpening?

I know this seems like a simple question but I’m new to unity so bare with me.

Don’t use mesh collider on a plane. It’s just too costly first of all. Use box collider. Make sure if isTrigger is not turned on. Add rigid body.