Changes to lists when structured topics are sent to RoboHelp

In FrameMaker I've created several DITA topics (no specializations, just topics) and included them in a ditamap. I mapped my Frame template styles to my RoboHelp .CSS styles. Then I linked to the ditamap from a RoboHelp HTML project. The topics came over and the style mappings work, but any <li> items with multiple elments are changed. For example, if I have this in my structured FrameMaker file:

<ul>

    <li>

        <p>This is the first list item.</p>

        <p>This is additional information about the first list item.</p>

    </li>

    <li>This is the second list item.</li>

    <li>This is the third list item.</li>

</ul>

I get this in my RoboHelp project:

<ul>

    <li>

        <p>This is the first list item.</p>

    </li>

</ul>

<p>This is additional information about the first list item.</p>

    <li>This is the secton list item.</li>

</ul>