[Plugin: BYOB Shopp Connect for Thesis] Weird behaviour when using Shopp sidebar

When I activate the Shopp Sidebar, my shopp storefront gets messed up. All the images disappear and the links no longer work. It probably has something to do with the code I use for the frontpage (it shows all the categories). I use this:

<?php
if(shopp('catalog','has-categories')): ?>
<ul class="products">
    <li class="grid">
        <ul>
                <?php while(shopp('catalog','categories')): ?>
                    <?php if(shopp('category','is-subcategory')):
                        continue;
                    endif; ?>
                    <li class="product">
                    <div class="frame">
                        <a href="<?php shopp('category','url'); ?>"><?php shopp('category','coverimage','setting=thumbnails'); ?></a>
                        <a href="<?php shopp('category','url'); ?>" class="category-link"><h4><?php shopp('category','name'); ?></h4></a>
                    </div>
                </li>
                <?php endwhile; ?>
        </ul>
    </li>
</ul>

<?php endif; ?>

<p><?php shopp('catalog','featured-products'); ?></p>

I hope you can help me, because I really like this plugin.

https://www.ads-software.com/extend/plugins/byob-shopp-connect-for-thesis/