title: Included ConstraintLayout with merge tag doesn't work
body: <p>This is my qff_layout.xml file</p>
  
  <pre><code>&lt;merge
  xmlns:app="http://schemas.android.com/apk/res-auto"
          xmlns:android="http://schemas.android.com/apk/res/android"
          xmlns:tools="http://schemas.android.com/tools"&gt;
  &lt;androidx.constraintlayout.widget.ConstraintLayout
          android:orientation="vertical"
          android:layout_width="match_parent"
          android:layout_height="wrap_content"&gt;
  
      &lt;com.google.android.material.textview.MaterialTextView
              android:id="@+id/questions_label"
              android:layout_width="0dp"
              android:layout_height="wrap_content"
              android:gravity="center"
              android:text="@string/questions"
              android:textSize="@dimen/text_normal"
              app:layout_constraintStart_toStartOf="parent"
              app:layout_constraintHorizontal_bias="0.5"
              app:layout_constraintEnd_toStartOf="@+id/followers_label"
              app:layout_constraintTop_toTopOf="parent"/&gt;
  
      &lt;com.google.android.material.textview.MaterialTextView
              android:id="@+id/followers_label"
              android:layout_width="0dp"
              android:layout_height="wrap_content"
              android:gravity="center"
              android:text="@string/followers"
              android:textSize="@dimen/text_normal"
              app:layout_constraintStart_toEndOf="@+id/questions_label"
              app:layout_constraintHorizontal_bias="0.5"
              app:layout_constraintEnd_toStartOf="@+id/following_label"
              app:layout_constraintTop_toTopOf="parent"/&gt;
  
      &lt;com.google.android.material.textview.MaterialTextView
              android:id="@+id/following_label"
              android:layout_width="0dp"
              android:layout_height="wrap_content"
              android:gravity="center"
              android:text="@string/following"
              android:textSize="@dimen/text_normal"
              app:layout_constraintStart_toEndOf="@+id/followers_label"
              app:layout_constraintHorizontal_bias="0.5"
              app:layout_constraintEnd_toEndOf="parent"
              app:layout_constraintTop_toTopOf="parent"/&gt;
  
      &lt;com.google.android.material.textview.MaterialTextView
              android:id="@+id/questions_number"
              android:layout_width="wrap_content"
              android:layout_height="wrap_content"
              android:gravity="center"
              android:textSize="@dimen/text_normal"
              android:textStyle="bold"
              tools:text="0"
              app:layout_constraintStart_toStartOf="@+id/questions_label"
              android:layout_marginEnd="8dp"
              app:layout_constraintEnd_toEndOf="@+id/questions_label"
              android:layout_marginRight="8dp"
              app:layout_constraintTop_toBottomOf="@+id/questions_label"/&gt;
  
      &lt;com.google.android.material.textview.MaterialTextView
              android:id="@+id/followers_number"
              android:layout_width="wrap_content"
              android:layout_height="wrap_content"
              android:gravity="center"
              android:textSize="@dimen/text_normal"
              android:textStyle="bold"
              tools:text="0"
              android:layout_marginStart="8dp"
              android:layout_marginLeft="8dp"
              android:layout_marginEnd="8dp"
              android:layout_marginRight="8dp"
              app:layout_constraintStart_toEndOf="@+id/questions_label"
              app:layout_constraintEnd_toStartOf="@+id/following_label"
              app:layout_constraintTop_toBottomOf="@+id/followers_label"/&gt;
  
  
      &lt;com.google.android.material.textview.MaterialTextView
              android:id="@+id/following_number"
              android:layout_width="wrap_content"
              android:layout_height="wrap_content"
              android:gravity="center"
              android:textSize="@dimen/text_normal"
              android:textStyle="bold"
              tools:text="0"
              android:layout_marginEnd="8dp"
              android:layout_marginRight="8dp"
              app:layout_constraintStart_toStartOf="@+id/following_label"
              app:layout_constraintEnd_toEndOf="@+id/following_label"
              app:layout_constraintTop_toBottomOf="@+id/following_label"/&gt;
  
  &lt;/androidx.constraintlayout.widget.ConstraintLayout&gt;
  &lt;/merge&gt;
  </code></pre>
  
  <p>This displays 6 textviews in two rows, something you would see in instagram app in profile section with Posts-Followers-Following and bellow numbers under each of those.
  Now the problem is when I include that in my main layout which is ConstraintLayout:
  profile_fragment.xml</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;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:orientation="vertical"
          android:layout_width="match_parent"
          android:layout_height="match_parent"&gt;
  
      &lt;androidx.appcompat.widget.Toolbar
              android:layout_width="0dp"
              android:layout_height="wrap_content"
              android:background="?attr/colorPrimary"
              android:theme="?attr/actionBarTheme"
              android:minHeight="?attr/actionBarSize"
              android:elevation="4dp"
              android:id="@+id/title"
              app:layout_constraintStart_toStartOf="parent"
              app:layout_constraintTop_toTopOf="parent"
              app:layout_constraintEnd_toEndOf="parent"/&gt;
  
      &lt;de.hdodenhof.circleimageview.CircleImageView
              android:id="@+id/profile_image"
              android:layout_width="80dp"
              android:layout_height="80dp"
              app:srcCompat="@drawable/ic_profile_24dp"
              tools:src="@drawable/ic_profile_24dp"
              app:civ_border_color="@color/secondaryDarkColor"
              app:civ_border_width="1dp"
              android:layout_marginTop="@dimen/spacing_normal"
              android:layout_marginStart="@dimen/spacing_normal"
              android:layout_marginLeft="@dimen/spacing_normal"
              app:layout_constraintTop_toBottomOf="@+id/title"
              app:layout_constraintStart_toStartOf="parent"/&gt;
  
      &lt;com.google.android.material.textview.MaterialTextView
              android:layout_width="0dp"
              android:layout_height="0dp"
              android:id="@+id/description"
              android:layout_marginEnd="@dimen/spacing_normal"
              android:layout_marginRight="@dimen/spacing_normal"
              android:layout_marginLeft="@dimen/spacing_normal"
              android:layout_marginStart="@dimen/spacing_normal"
              app:layout_constraintStart_toEndOf="@+id/profile_image"
              app:layout_constraintEnd_toEndOf="parent"
              app:layout_constraintBottom_toBottomOf="@+id/profile_image"
              app:layout_constraintTop_toTopOf="@+id/profile_image"/&gt;
  
      &lt;include
              layout="@layout/qff_layout"
              android:id="@+id/qff_layout"
              android:layout_width="0dp"
              android:layout_height="wrap_content"
              android:layout_marginTop="@dimen/spacing_small"
              app:layout_constraintTop_toBottomOf="@+id/profile_image"
              app:layout_constraintEnd_toEndOf="parent"
              app:layout_constraintStart_toStartOf="parent"/&gt;
  
      &lt;com.google.android.material.tabs.TabLayout
              android:id="@+id/sliding_tabs"
              android:layout_width="0dp"
              android:layout_height="wrap_content"
              android:background="@color/primaryLightColor"
              app:tabMode="fixed"
              app:layout_constraintEnd_toEndOf="parent"
              app:layout_constraintStart_toStartOf="parent"
              app:layout_constraintTop_toBottomOf="@+id/qff_layout"/&gt;
  
      &lt;androidx.viewpager.widget.ViewPager
              android:id="@+id/view_pager"
              android:layout_width="0dp"
              android:layout_height="0dp"
              android:background="@android:color/white"
              app:layout_constraintBottom_toBottomOf="parent"
              app:layout_constraintEnd_toEndOf="parent"
              app:layout_constraintStart_toStartOf="parent"
              app:layout_constraintTop_toBottomOf="@+id/sliding_tabs" /&gt;
  
  &lt;/androidx.constraintlayout.widget.ConstraintLayout&gt;
  </code></pre>
  
  <p>Nothing gets displayed.<br>
  I tried changing my main layout to linear and it's the same.<br>
  But when I remove merge tag from qff_layout.xml and use the same include tag in main layout it works well and displays the qff_layout, How??Why??<br>
  What is the use of merge tag then, please do not quote something from the stupidest documentation ever because it makes no sense.</p>