почему я не вижу красный квадрат в MotionLayout?

Подскажите, пожалуйста, почему я не вижу красный квадрат в MotionLayout. Я программно делаю анимацию. Добавляю View в motionLayout, затем создаю transition. Что я не так делаю? Хочу программно добавлять изображения и программно управлять стартом и эндом transition.

    protected void onCreate(Bundle savedInstanceState) {
                super.onCreate(savedInstanceState);
                setContentView(R.layout.activity_main);
                MotionLayout motionLayout = (MotionLayout) findViewById(R.id.motionLayout);
        
                MotionLayout.LayoutParams layoutParams = new MotionLayout.LayoutParams
                        (100, 100);
                
                int count = 1;
                View[] buttons = new View[count];
                for (int i = 0; i < count; i++) {
                    
                    buttons[i] = new View(MainActivity.this);
        
                    buttons[i].setId(getViewId(i));
                    buttons[i].setBackgroundColor(Color.RED);
                    motionLayout.addView(buttons[i], layoutParams);
        
                    MotionScene motionScene = new MotionScene(motionLayout);
                    MotionScene.Transition transition = createTransition(motionScene, motionLayout, buttons[i]);
        
                    motionScene.addTransition(transition);
                    motionScene.setTransition(transition);
           }
        }
    
    
    private MotionScene.Transition createTransition(MotionScene scene, MotionLayout motionLayout, View view) {
            int startSetId = View.generateViewId();
            ConstraintSet startSet = new ConstraintSet();
    
            startSet.constrainHeight(view.getId(),
                    50);
            startSet.constrainWidth(view.getId(),
                    50);
    
            startSet.connect(view.getId(), ConstraintSet.LEFT,
                    ConstraintSet.PARENT_ID, ConstraintSet.LEFT, 0);
            startSet.connect(view.getId(), ConstraintSet.RIGHT,
                    ConstraintSet.PARENT_ID, ConstraintSet.RIGHT, 0);
            startSet.connect(view.getId(), ConstraintSet.TOP,
                    ConstraintSet.PARENT_ID, ConstraintSet.TOP, 0);
    
            startSet.applyTo(motionLayout);
    
            int endSetId = View.generateViewId();
            ConstraintSet endSet = new ConstraintSet();
    
            endSet.constrainHeight(view.getId(),
                    50);
            endSet.constrainWidth(view.getId(),
                    50);
    
            endSet.connect(view.getId(), ConstraintSet.LEFT,
                    ConstraintSet.PARENT_ID, ConstraintSet.LEFT, 0);
            endSet.connect(view.getId(), ConstraintSet.RIGHT,
                    ConstraintSet.PARENT_ID, ConstraintSet.RIGHT, 0);
            endSet.connect(view.getId(), ConstraintSet.BOTTOM,
                    ConstraintSet.PARENT_ID, ConstraintSet.BOTTOM, 0);
    
            endSet.applyTo(motionLayout);
    
            int transitionId = View.generateViewId();
    
            return TransitionBuilder.buildTransition(
                    scene,
                    transitionId,
                    startSetId, startSet,
                    endSetId, endSet);
        }

Разметка

<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/constraintlayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <androidx.constraintlayout.motion.widget.MotionLayout
        android:id="@+id/motionLayout"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="#7C7C7C"
        app:layoutDescription="@xml/scene_01"
        android:layout_margin="50dp"
        tools:showPaths="true">

</androidx.constraintlayout.motion.widget.MotionLayout>
</androidx.constraintlayout.widget.ConstraintLayout>

<?xml version="1.0" encoding="utf-8"?>
<MotionScene xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:motion="http://schemas.android.com/apk/res-auto">
</MotionScene>