Show_content doesn't make any difference

I tested it and show_content param works good for me.
Please, re-check everything, try to re-type shortcode or re-install plugin or try to test shortcode on other pages.
Also check other plugins which can modify content in some-way and could create conflict with this shortcode.

You are right…

wordpress inserted a bunch of “code” tags which got everything confused.

<p><code><code>[jcolumns]</code></code></p>
<h5><code><code>Workshop [description]<br /></code></code></h5>
<p><code><code><code>[pagelist_ext child_of="1327" image_width="50" image_height="50"<code><code><code><code><code><code>show_content="0"</code></code></code></code></code></code>]</code>[jcol/]</code></code></p>
<h5><code><code>Ongoing Groups [description]<br /></code></code></h5>
<p><code><code><code><code><code>[pagelist_ext child_of="52" image_width="50" image_height="50" <code>show_content="0"</code>]</code></code></code>[/jcolumns]</code></code></p>

No idea how that happened.

Thank you!