Why is my select meta data not saving?

I am working on a site at the moment where I need to save several different types of meta data for a custom post type.

At present I have a text input that is saving with no problem but am struggling to get a select field to do the same.

This is the function that outputs the select field:

function kwi_department_input() {
    // Define function to create meta box for team member department.

    global $post;
    echo '<input type="hidden" name="teammeta_noncename" id="teammeta_noncename" value="' . wp_create_nonce(plugin_basename(__FILE__)) . '" />';
    $department = get_post_meta($post->ID, '_department', true); ?>

    <select name="_department" id="_department">
        <option value="Directors" <?php selected($department, 'Directors'); ?>>Directors</option>
        <option value="Finance / Admin" <?php selected($department, 'Finance / Admin'); ?>>Finance / Admin</option>
        <option value="Customer Service Team" <?php selected($department, 'Customer Service Team'); ?>>Customer Service Team</option>
        <option value="Commercial Team" <?php selected($department, 'Commercial Team'); ?>>Commercial Team</option>
    </select>
<?php }

And this is the function that saves all of the data:

function kwi_save_team_meta($post_id) {
    if( !wp_verify_nonce( $_POST['teammeta_noncename'], plugin_basename(__FILE__) )) {
        return $post_id;
    }

    if( !current_user_can( 'edit_post', $post_id ) ) {
        return $post_id;
    }

    $team_meta = array(
        '_department' => $_POST['_department'], 
        '_languages' => $_POST['_languages'] // Languages is the text input that is saving with no issue.
    );

    foreach($team_meta as $key => $value) {
        if(get_post_meta($post_id, $key, FALSE)) {
            update_post_meta($post_id, $key, $value);
        } else {
            add_post_meta($post_id, $key, $value);
        }
        if(!$value) {
            delete_post_meta($post_id, $key);
        }
    }
}

Any pointers as to what I’m doing wrong would be much appreciated.