Child Theme Reverts to Parent Theme After Activation: Customizations Lost

This problem may have several underlying causes. I encourage you to create your child theme from scratch and make sure working fine without any deep customization.

Practically speaking, the child theme works fine with the style.css and the functions.php file only.

/*
Theme Name:   Drinkify Lite Child
Template:     drinkify-lite
Version:      1.0.0
*/

body {
    background: green;
}

Create the functions.php file in the child directory (drinkify-lite-child) something similar:

<?php

function drinkify_light_child_enqueue_styles() {

    $parent_style="drinkify-lite-style";

    wp_enqueue_style( $parent_style, get_template_directory_uri() . '/style.css' );
    wp_enqueue_style( 'drinkify_light-child-style',
        get_stylesheet_directory_uri() . '/style.css',
        array( $parent_style )
    );
}
add_action( 'wp_enqueue_scripts', 'drinkify_light_child_enqueue_styles' );

/* --------- Insert your customized functions on the next rows --------- */

And then add your customization functions one by one and see which one causing the problem.

Read more about the child theme here.