Change PMPro CPT to redirect to the login page instead of the chosen "Redirect To" page if the user is logged out.

my_pmprocpt_redirect_to.php

/*
	Change PMPro CPT to redirect to the login page instead of the chosen "Redirect To" page
	if the user is logged out.
*/
function my_pmprocpt_redirect_to($redirect_to) {
	if(!is_user_logged_in()) {
		$redirect_to = wp_login_url($_SERVER['REQUEST_URI']);
	}

	return $redirect_to;
}
add_action('pmprocpt_redirect_to', 'my_pmprocpt_redirect_to');