OK, I think I get it. You are grouping on a string derived from the node name instead of the node itself. This doesn't work for my general intent, because the other elements may not all be the same. For example, I might have this:

<steps>

<step>

<para>Intro stuff</para>

<para>More intro stuff</para>

<figure/>

<figure/>

<para>Conclusion stuff</para>

<table>More conclusion stuff</table>

<para>More conclusion stuff</para>

</step>

</steps>

and I would want the three elements following the last figure to be in a single group.