Texts don’t even appear on the button

Question

Good Afternoon!

I have the following XML:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="16dp"
    tools:context=".Principal">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">
       <TextView
           android:id="@+id/tv1"
           android:layout_width="match_parent"
           android:layout_height="wrap_content"
           android:layout_marginTop="50dp"
           android:width="200dp"
           android:textAlignment="center"
           tools:text="Logon" />

    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">

        <LinearLayout
            android:layout_width="70dp"
            android:layout_height="80dp"
            android:orientation="vertical">

            <TextView
                android:id="@+id/tvLogin"
                android:layout_width="match_parent"
                android:layout_height="30dp"
                android:layout_marginTop="10dp"
                tools:text="Login" />

            <TextView
                android:id="@+id/tvSenha"
                android:layout_width="match_parent"
                android:layout_height="30dp"
                android:layout_marginTop="10dp"
                tools:text="Senha" />
        </LinearLayout>


        <LinearLayout
            android:layout_width="280dp"
            android:layout_height="80dp"
            android:orientation="vertical">

            <EditText
                android:id="@+id/txtLogin"
                android:layout_width="wrap_content"
                android:layout_height="30dp"
                android:layout_weight="1"
                android:ems="10"
                android:inputType="text" />

            <EditText
                android:id="@+id/txtSenha"
                android:layout_width="wrap_content"
                android:layout_height="30dp"
                android:layout_weight="1"
                android:ems="10"
                android:inputType="textPassword" />
        </LinearLayout>

    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">

        <Button
            android:id="@+id/btnLogar"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="20dp"
            tools:text="Logar" />

    </LinearLayout>


</LinearLayout>

And the code corresponding java:

package carcleo.com.cadastro;

import android.app.Activity;
import android.os.Bundle;

public class Principal extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.principal);
    }
}

And the following layout was generated in Android Studio.

It turns out that when I compile in device (Moto G 4 Play), does not appear any TextView not even the text of the button.

Where am I going wrong?

Follow image of the form on Android Studio

No device, the words

Logon, Login, Password, LOG IN

Do not appear.

But it seems that the elements are there occupying the space.