Why doesn't the radial gradient of the buttons show up on a real device?

Question

Android

In Android studio, the gradient in the center of the buttons is displayed perfectly, but in my smartphone (Doogee dg700, Android 4.4.2) this gradient is not at all, what is the reason?
Picture from Android studio:

Picture from my smartphone:

Layout of the whole layout:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity"
    android:background="@color/colorPrimary"
    android:padding="10dp"
    android:gravity="center"
    android:orientation="vertical">
    
    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="horizontal">

        <Button
            android:background="@drawable/blue_button"
            android:onClick="playsound1"
            android:layout_width="100dp"
            android:layout_height="100dp"/>
        <Button
            android:layout_marginLeft="5dp"
            android:background="@drawable/blue_button"
            android:onClick="playsound2"
            android:layout_width="100dp"
            android:layout_height="100dp"/>
        <Button
            android:layout_marginLeft="5dp"
            android:background="@drawable/blue_button"
            android:onClick="playsound3"
            android:layout_width="100dp"
            android:layout_height="100dp"/>

    </LinearLayout>

    <LinearLayout
        android:layout_marginTop="5dp"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="horizontal">

        <Button
            android:background="@drawable/purple_button"
            android:onClick="playsound4"
            android:layout_width="100dp"
            android:layout_height="100dp"/>
        <Button
            android:layout_marginLeft="5dp"
            android:background="@drawable/orange_button"
            android:onClick="playsound5"
            android:layout_width="100dp"
            android:layout_height="100dp"/>
        <Button
            android:layout_marginLeft="5dp"
            android:background="@drawable/pink_button"
            android:onClick="playsound6"
            android:layout_width="100dp"
            android:layout_height="100dp"/>

    </LinearLayout>

    <LinearLayout
        android:layout_marginTop="5dp"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="horizontal">

        <Button
            android:background="@drawable/green_button"
            android:onClick="playsound7"
            android:layout_width="100dp"
            android:layout_height="100dp"/>
        <Button
            android:layout_marginLeft="5dp"
            android:background="@drawable/green_button"
            android:onClick="playsound8"
            android:layout_width="100dp"
            android:layout_height="100dp"/>
        <Button
            android:layout_marginLeft="5dp"
            android:background="@drawable/pink_button"
            android:onClick="playsound9"
            android:layout_width="100dp"
            android:layout_height="100dp"/>

    </LinearLayout>

</LinearLayout>

Labeling one of the buttons:

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
<item android:state_pressed="false">
    <shape android:shape="rectangle">
        <gradient android:startColor="@color/pinkStartColor"
            android:endColor="@color/pinkEndColor"
            android:type="radial"
            android:angle="90"
            android:gradientRadius="50dp"/>
        <corners android:radius="30dp"/>
    </shape>
</item>

    <item android:state_pressed="true">
        <shape android:shape="rectangle">
            <gradient android:startColor="@color/pinkStartColor"
                android:endColor="@color/pinkEndColor"
                android:type="radial"
                android:angle="90"
                android:gradientRadius="100dp"/>
            <corners android:radius="30dp"/>
        </shape>
    </item>
</selector>