未为TextView显示高程。下面是一个布局：

<?xml version="1.0" encoding="utf-8"?>
<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:layout_width="match_parent"
    android:layout_height="wrap_content"
    tools:context=".presentation.TrainingListFragment">

    <androidx.appcompat.widget.AppCompatTextView
        android:id="@+id/schedule_label"
        style="@style/Widget.AppCompat.TextView"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:background="@drawable/background_selector"
        android:elevation="15dp"
        android:fontFamily="@font/inter_medium"
        android:gravity="center_horizontal|center_vertical"
        android:outlineProvider="none"
        android:text="@string/schedule"
        android:textColor="@color/black"
        android:textSize="20sp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/rv_list_of_date"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="65dp"
        app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/schedule_label"
        tools:listitem="@layout/list_of_days_item" />

</androidx.constraintlayout.widget.ConstraintLayout>

这是TextView的背景选择器：

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">
    <solid android:color="@color/bottom_bar_background" />
    <corners android:radius="5dp" />
</shape>

我尝试了所有的建议从Elevation on Android Lollipop not working和从这里Android "elevation" not showing a shadow
我想不出原因是什么。你的建议？！