1. DIVI does definitely not load Bootstrap.
As such, in DIVI original Theme, you need to use "Toolset should load Bootstrap 3.0".
2. I created a Child theme according the Codex:
https://codex.wordpress.org/Child_Themes
This works perfectly fine.
Required files are functions.php and style.css both inside the Child Directory.
Required is that functions.php of the Child has at the very least:
<?php
add_action( 'wp_enqueue_scripts', 'my_theme_enqueue_styles' );
function my_theme_enqueue_styles() {
wp_enqueue_style( 'divi-style', get_template_directory_uri() . '/style.css' );
}
?>
The style.css at least must have:
/*
Theme Name: DIVI Child
Theme URI: <em><u>hidden link</u></em>
Description: DIVI Child Theme
Author: John Doe
Author URI: <em><u>hidden link</u></em>
Template: divi
Version: 1.0.0
License: GNU General Public License v2 or later
License URI: <em><u>hidden link</u></em>
Tags: any, another
Text Domain: divi-child
*/
This works.
3. I cannot assist builds of other Plugins.
4. I checked the Child Theme you provided, and it doesn't work.
==> I then re-enabled my own child theme, and now also that does not work anymore 🙁
5. I could not believe it, re-did all the steps, and it failed again.
So, I cannot tell what is wrong, but it's not working, not even anymore with a proper DIVI Child Theme.
There are no JS errors, and nothing else that would point to the issue.
It works just fine with any other theme.
As such I suspect, there is an issue with the integration of the Theme (DIVI is integrated).
Maybe we do not consider Child Themes, although, the the_content() is properly overwritten by Layouts, perhaps we do not properly enqueue Bootstrap in those cases.
But then, it works on Twenty Seventeen, which is not even integrated right now (unless you use the bridge plugin)
I need some more time on this and will get back at you as soon I have at least a plausible reason on why it's not working with DIVI.