Listitem Lines Wrapping - Changes Spacing

Hello,

I am working on an APP stylesheet in Styler 8.1.2. The XML (Docbook) contains some simple ordered and itemized lists - when I preview or publish to PDF, long lines which wrap are causing the entire sentence to drop down by one line relative to the item.

The code that produces the above is as follows:

<orderedlist>
<listitem>
<para><?Pub _font Posture="italic"?>Line 1<?Pub /_font?></para>
</listitem>
<listitem>
<para>Line 2. Form 6377, VHP Series Four P9394GSI with ESM Operation
&amp; Maintenance Manual (previous production engines)</para>
</listitem>
</orderedlist><itemizedlist>
<listitem>
<para><?Pub _font Posture="italic"?>Line 1<?Pub /_font?></para>
</listitem>
<listitem>
<para>Line 1 &amp; 2. Form 6377, VHP Series Four</para>
</listitem>
</itemizedlist><itemizedlist>
<listitem>
<para>Form 6377, VHP Series Four P9394GSI with ESM Operation &amp;
Maintenance Manual (previous production engines)</para>
</listitem>
<listitem>
<para>Form 6398, VHP Series Four P9394GSI with AFR2/emPact Emissions
Control System Operation &amp; Maintenance Manual (current production
engines)</para>
</listitem>
</itemizedlist>

None of the changes I make to the elements in Styler make any difference to the output.

Does anyone have any idea what might be causing this, and a way to fix this problem?

Many thanks in advance

John