My new theme doesn't show the slogan
Let's call it a bug in Nexus theme. 

If you sub-themed Nexus, copy the page.tpl.php from Nexus templates folder into your sub-theme's template folder, then make the following change to the copied file, just after the h1 tag for the title:

// look for this
&lt;h1 id="site-title"&gt;
  &lt;a href="&lt;?php print $front_page; ?&gt;" title="&lt;?php print t('Home'); ?&gt;"&gt;&lt;?php print $site_name; ?&gt;&lt;/a&gt;
&lt;/h1&gt;
// then add this below it
&lt;?php if ($site_slogan): ?&gt;
  &lt;div id="site-slogan"&gt;
    &lt;?php print $site_slogan; ?&gt;
  &lt;/div&gt;
&lt;?php endif; ?&gt;