Invalid captcha token - MB User Profile Register Form

Hi there I am using the MB User Profile extension to allow users to register on a site.

The Issue
============
After adding a valid (V3) recaptcha_key and recaptcha_secret to the [mb_user_profile_register] shortcode and submitting a valid user registration, I get a WP Error: <div class="wp-die-message">Invalid captcha token</div>. Furthermore, I see a 500 Internal Server Error in the browser console.

If you remove the recaptcha_key and recaptcha_secret the registration form successfully submits without error.

To confirm that this problem was NOT isolated to my specific site setup I recreated the issue in a completely clean install of WordPress locally with a basic WP Theme.

Re-Create The issue
=======================
To re-create this issue follow these steps:

1) Create a new clean local dev environment using:
- NGINX
- MYSQL 8.0.35
- PHP 8.3
- SSL
2) Install WordPress latest stable version 6.7.2.
3) Install & Activate Metabox plugin.
4) Install & Activate Metabox AIO plugin.
5) Create a very basic custom PHP Page Template and assign it to a WordPress page:

<?php
/**
 * Template Name: Frontend Register
 */

// Exit if accessed directly.
defined( 'ABSPATH' ) || exit;

get_header();

?>

<div id="page-wrapper">
    <div class="wrapper">
        <div class="container">
            <div class="row">
                <div class="col-md-12">
                    <?php
                     echo do_shortcode('[mb_user_profile_register password_strength="false" recaptcha_key="" recaptcha_secret=""]'); 
                    ?>
                </div><!-- .col-md-12 -->
            </div><!-- .row -->
        </div><!-- .container -->
   
</div><!-- .wrapper -->

<?php wp_footer(); ?>

6) Generate valid recaptcha site key and secret key and enter into shortcode.
7) Visit the new WordPress Page with Shortcode Form and submit a new user registration.

I have no errors showing in my debug.log for this scenario.
I have also created and used (V3) recaptcha site keys and secret keys on the MB Frontend Submission Form shortcode and this issue is NOT present here!

I look forward to your response.

Cheers 🙂