Get Rounded Corners In MaterialCardView

I am trying to get rounded gridview corners using a MaterialCardView, the rounded frame for each image item shows correctly during a blank placeholder but as soon as images are loaded they overlap the rounded corners and display as squares.

XML Code:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:orientation="vertical"
>
<RelativeLayout
    android:layout_width="wrap_content"
    android:layout_height="160dp"
    android:layout_weight="1"
    >
    <com.google.android.material.card.MaterialCardView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:cardCornerRadius="8dp"
        android:layout_margin="5dp"
        android:elevation="10dp"
        android:descendantFocusability="blocksDescendants"
        >
        <ImageView
            android:id="@+id/ivImage"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:src="@drawable/ic_launcher_background"
            android:scaleType="centerCrop"
            />
        <ImageButton
            android:id="@+id/ibDots"
            android:layout_width="wrap_content"
            android:layout_height="35dp"
            android:src="@drawable/ic_more_vert_white_24dp"
            android:scaleType="fitCenter"
            android:layout_gravity="right"
            android:background="@android:color/transparent"
            />
        <ImageView
            android:id="@+id/ivCheckbox"
            android:layout_width="35dp"
            android:layout_height="35dp"
            android:scaleType="fitEnd"
            android:src="@drawable/ic_check_box_empty_black_24dp"
            android:layout_gravity="bottom|right"
            android:elevation="10dp"
            android:alpha="0.7"
            />
    </com.google.android.material.card.MaterialCardView>

</RelativeLayout>
</LinearLayout>