The problem seem to come from <br/> in <p> : test with this markup :

<p>Header <br /> First list element <br />Second list element<br /> third list element<br /> footer</p>

Try creating a square list from "First list element" to "third list element" included.

The result markup is :

<p>Header</p>
<ul class="disc">
<li> First list element </li>
<li>Second list element</li>
<li> third list element</li>
</ul>
<p>footer</p>

but should be :

<p>Header</p>
<ul class="square">
<li> First list element </li>
<li>Second list element</li>
<li> third list element</li>
</ul>
<p>footer</p>