I found the fix for this:
BoardIndex.template.php
<header class="category_header">';
// If this category even can collapse, show a link to collapse it.
if ($category['can_collapse'])
echo '
<a class="chevricon i-chevron-', $category['is_collapsed'] ? 'down' : 'up', '" href="', $category['collapse_href'], '" title="', $category['is_collapsed'] ? $txt['show'] : $txt['hide'], '"></a>';
// The "category link" is only a link for logged in members. Guests just get the name.
echo '
', $category['link'], '
</header>