Add below code in Child theme functions.php or in WP Admin - Plugins - Editor - WPLMS Customizer - wplms_Customizer.php
add_action('wplms_before_single_assignment','wplms_check_wplms_assignment_submission');
function wplms_check_wplms_assignment_submission(){
if(is_user_logged_in()){
$user_id = get_current_user_ID();
$assignment_id = get_the_ID();
$status = get_post_meta($assignment_id,$user_id,true);
echo $status.'###';
if(isset($status) && is_numeric($status)){
if(!$status){
wp_die('Assignment under evaluation');
}else{
$link = bp_core_get_user_domain($user_id).BP_COURSE_SLUG.'/'.BP_COURSE_RESULTS_SLUG.'/?action='.$assignment_id;
?>
<script type="text/javascript">
window.location= <?php echo "'" . $link . "'"; ?>;
</script>
<?php
}
}
}
}