Right and Bottom Constraint on FloatingActionButton makes it unseen : <p>I have a <code>FloatingActionButton</code> inside a <code>ConstraintLayout</code>, like so:</p>

<pre class="lang-xml prettyprint-override"><code>&lt;android.support.constraint.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"&gt;

    &lt;android.support.design.widget.FloatingActionButton
                android:id="@+id/fab_add_topic"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                app:srcCompat="@drawable/ic_add"
                app:layout_constraintRight_toLeftOf="parent"
                app:layout_constraintBottom_toTopOf="parent"
                android:foregroundGravity="right|bottom"
                android:layout_marginRight="@dimen/material_tooltip_margin_top"
                android:layout_marginBottom="@dimen/material_tooltip_margin_top"
                android:elevation="6dp"
                app:pressedTranslationZ="12dp"
                app:borderWidth="0dp"/&gt;

&lt;/android.support.constraint.ConstraintLayout&gt;
</code></pre>

<p>However, as I inflate the layout on a <code>Fragment</code> with Android Databinding (on a Kotlin class), it does not appear.</p>

<p>I attempted to implement the solutions mentioned here, still inside the <code>ConstraintLayout</code> : <a href="https://stackoverflow.com/questions/30769080/bottom-align-floating-action-button">Bottom Align Floating Action Button</a></p>

<p>It appears just fine if I display it with Top and Left constraints.</p>

<p>Anything I missed? Thanks!</p>
