So open up /class/frontend-form.php
line 270, you'll see this code wp_set_post_terms( $post_id, $_POST[$taxonomy['name']], $taxonomy['name'] );
, replace this with the code below and should be working:
[php]
if ( is_taxonomy_hierarchical( $taxonomy[‘name'] ) ) {
wp_set_post_terms( $post_id, $_POST[$taxonomy[‘name']], $taxonomy[‘name'] );
} else {
if ( $tax ) {
$non_hierarchical = array();
foreach ($tax as $value) {
$term = get_term_by( ‘id', $value, $taxonomy[‘name'] );
if ( $term && !is_wp_error( $term ) ) {
$non_hierarchical[] = $term->name;
}
}
wp_set_post_terms( $post_id, $non_hierarchical, $taxonomy[‘name'] );
}
} // hierarchical
[/php]