Solution of : Conflict with the Registration Module of LearnDash
LearnDash is a WordPress learning management system, and if you're using it while Ultimate Member is activated, you might encounter a conflict with the registration module of LearnDash.
Adding the following code below in the child theme's functions.php will help you solve the issue:
remove_action( 'login_form_register', 'um_form_register_redirect', 10 );