inside list layout

I'm using the following <grouplist> of controls so that the middle <textbox> can have a variable height and the bottom label  will always be just below it regardless of the <textbox>'s text length.

        

<control type="grouplist">

  <width>600</width>

  <height>600</height>

  <control type="label">

    <width>600</width>

    <height>48</height>

    <font>TitleFont</font>

    <textcolor>TextBright</textcolor>

    <label>$INFO[ListItem.Label]</label>

  </control>

  <control type="textbox">

    <width>600</width>

    <height max="178">auto</height>

    <font>PlotFont</font>

    <textcolor>TextDim</textcolor>

    <align>left</align>

    <aligny>top</aligny>

    <label>$INFO[ListItem.Plot]</label>

    <wrapmultiline>true</wrapmultiline>

  </control>

  <control type="label">

    <width>600</width>

    <height>48</height>

    <font>InfoFont</font>

    <label>$INFO[ListItem.Duration(mm)]mins   $INFO[ListItem.Date]   $INFO[ListItem.VideoResolution]p   $INFO[ListItem.AudioCodec]</label>

  </control>

</control>

This works perfectly when I place the <grouplist> directly in a window.

However it completely fails to display when I place it into a <list>'s <itemlayout> or <focusedlayout>.

Any ideas why it fails, or is there another way to replicate the same effect inside of a layout?