internal link in sitemap.xml

Question

I have a codeigniter site, it have sitemap.xml but I want to insert there post tags links too.

<!-- Start tags -->
<?php $tags=explode(',', $watch_videos->tags); foreach ($tags as $tag):?>
<url>
    <loc><?php echo base_url().'tags/'.$tag.'.html'; ?>"></loc>
    <priority>0.5</priority>
</url>
<?php endforeach; ?>
<!-- End tags -->

I am writing this and It only comes one link with

https://kinogo.ge/tags/.html

For example Genre links work perfect and is written like this:

<!-- Start Genre -->
<?php foreach($genres as $genre): ?>
<url>
    <loc><?php echo base_url()."genre/".$genre['slug'].'.html';?></loc>
    <priority>0.5</priority>
</url>
<?php endforeach; ?>
<!-- End Genre -->

Here is How tags appear in videos internal link

<?php if ($watch_videos->tags !='' && $watch_videos->tags !=NULL): ?>
                <div class="tags">
                    <h3 class="sidebar-title">Tags</h3>
                    <ul class="list-inline list-unstyled">
                    <?php $tags=explode(',', $watch_videos->tags);
                    foreach ($tags as $tag):
                    ?>
                        <li><h2><a href="<?php echo base_url().'tags/'.$tag.'.html'; ?>"><?php echo $tag; ?></a></h2></li>
                    <?php endforeach; ?>
                    </ul>
                </div>
            <?php endif; ?>