title: MotionLayout keyTrigger doesn't work properly?
body: <p>I have MotionLayout xml file </p>
  
  <p>
  </p>
  
  <pre><code>&lt;androidx.constraintlayout.motion.widget.MotionLayout
      android:id="@+id/motionLayout"
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      android:background="#1e376b"
      app:layoutDescription="@xml/motion_layout_header_scene"&gt;
  
      &lt;ImageView
          android:id="@+id/background"
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          android:background="@color/colorAccent"
          android:scaleType="centerCrop"
          app:srcCompat="@drawable/icon_schiller"
          tools:ignore="MissingConstraints" /&gt;
  
  
  &lt;/androidx.constraintlayout.motion.widget.MotionLayout&gt;
  
  &lt;androidx.core.widget.NestedScrollView
      android:id="@+id/scrollable"
      android:layout_width="match_parent"
      android:layout_height="match_parent"&gt;
  
      &lt;TextView
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          android:layout_margin="16dp"
          android:text=“@string/long_text /&gt;
  &lt;/androidx.core.widget.NestedScrollView&gt;
  
  &lt;com.google.android.material.floatingactionbutton.FloatingActionButton
      android:id="@+id/fab"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_margin="16dp"
      android:clickable="true"
      app:layout_constraintBottom_toBottomOf="parent"
      app:layout_constraintRight_toRightOf="parent"
      app:srcCompat="@android:drawable/ic_input_add" /&gt;
  </code></pre>
  
  <p></p>
  
  <p>and here is my scene file</p>
  
  <p>
  </p>
  
  <pre><code>&lt;Transition
      motion:constraintSetEnd="@+id/end"
      motion:constraintSetStart="@+id/start"
      motion:duration="250"
      motion:motionInterpolator="linear"&gt;
  
      &lt;OnSwipe
          motion:dragDirection="dragUp"
          motion:touchAnchorId="@+id/motionLayout"
          motion:touchAnchorSide="bottom" /&gt;
  
      &lt;KeyFrameSet&gt;
  
          &lt;KeyTrigger
              motion:framePosition="20"
              motion:motionTarget="@id/fab"
              motion:onPositiveCross="hide" /&gt;
  
          &lt;KeyTrigger
              motion:framePosition="40"
              motion:motionTarget="@id/fab"
              motion:onNegativeCross="show" /&gt;
      &lt;/KeyFrameSet&gt;
  &lt;/Transition&gt;
  
  &lt;ConstraintSet android:id="@+id/start"&gt;
      &lt;Constraint
          android:id="@id/motionLayout"
          android:layout_width="match_parent"
          android:layout_height="200dp"
          motion:layout_constraintTop_toTopOf="parent" /&gt;
  
      &lt;Constraint
          android:id="@id/scrollable"
          android:layout_width="match_parent"
          android:layout_height="0dp"
          motion:layout_constraintBottom_toBottomOf="parent"
          motion:layout_constraintTop_toBottomOf="@+id/motionLayout" /&gt;
  &lt;/ConstraintSet&gt;
  
  &lt;ConstraintSet android:id="@+id/end"&gt;
      &lt;Constraint
          android:id="@id/motionLayout"
          android:layout_width="match_parent"
          android:layout_height="56dp"
          motion:layout_constraintTop_toTopOf="parent"
          motion:progress="1" /&gt;
  
      &lt;Constraint
          android:id="@id/scrollable"
          android:layout_width="match_parent"
          android:layout_height="0dp"
          motion:layout_constraintBottom_toBottomOf="parent"
          motion:layout_constraintTop_toBottomOf="@+id/motionLayout" /&gt;
  &lt;/ConstraintSet&gt;
  </code></pre>
  
  <p></p>
  
  <p>But you can see in the video there are issues with fab when scrolling up it disappears and then when I scroll down it doesn't appear again.
  <a href="https://drive.google.com/file/d/1-V5EAdKd0EDfYOKE0ElgfEOSOoUUZrCK/view?usp=sharing" rel="nofollow noreferrer">https://drive.google.com/file/d/1-V5EAdKd0EDfYOKE0ElgfEOSOoUUZrCK/view?usp=sharing</a></p>