Box collision smaller than visual component?

[ViaCognita]

I’m learning Unreal Engine developing Pong game.

Now I’m working with Collisions. Any idea about why the box stops in the middle of the floor? I press S key to move the box down and it stops in the middle of the floor. Look:

I have added a Collision box to the floor and set it to BlockAll and it stops as you can see. I’m thinking if the collision box inside the box is smaller than the visual component and this is why it stops in the middle.

This is box constructor code:

APaddle::APaddle()
{
 	// Set this pawn to call Tick() every frame.  You can turn this off to improve performance if you don't need it.
	PrimaryActorTick.bCanEverTick = true;

	// Our root component will be a box that reacts to physics and to interact with physical world.
	BoxComponent = CreateDefaultSubobject<UBoxComponent>(TEXT("BoxComponent"));
	RootComponent = BoxComponent;
	BoxComponent->InitBoxExtent(FVector(20.0f, 20.0f, 20.0f));

	// Create and position a mesh component so we can see where our paddle is.
	PaddleVisual = CreateDefaultSubobject<UStaticMeshComponent>(TEXT("PaddleVisualRepresentation"));
	PaddleVisual->SetupAttachment(RootComponent);

	SetActorEnableCollision(true);
	
	BoxComponent->SetCollisionProfileName(TEXT("BlockAll")); // or BoxComponent->SetCollisionResponseToAllChannels(ECollisionResponse::ECR_Block);

	// Add a visual cuboid to see it.
	static ConstructorHelpers::FObjectFinder<UStaticMesh> CuboidVisualAsset(TEXT("/Engine/EditorMeshes/EditorCube.EditorCube"));
	if (CuboidVisualAsset.Succeeded())
	{
		PaddleVisual->SetStaticMesh(CuboidVisualAsset.Object);
		static ConstructorHelpers::FObjectFinder<UMaterial> GreenGrassMaterial (TEXT("/Game/Materials/M_Grass.M_Grass"));
		if (GreenGrassMaterial.Succeeded())
		{
			PaddleVisual->SetMaterial(0, GreenGrassMaterial.Object);
		}
	}

	// Take control of the default player
	AutoPossessPlayer = EAutoReceiveInput::Player0;

	// Create an instance of our movement component, and tell it to update our root component.
	OurMovementComponent = CreateDefaultSubobject<UPaddleMovementComponent>(TEXT("PaddleCustomMovementComponent"));
	OurMovementComponent->UpdatedComponent = RootComponent;
}

You can download the project here: https://github.com/ViaCognita/PongGame