Could it be that it is the fact that the locationmap lookup in the sitemap is specified as element content, and not as an attribute value? All other examples I have found using lm has the lm lookup in an attribute. That is, I'm thinking that this case is not so much tested compared to the usual case, and that there might be some bugs lurking in the code somewhere.

I'm pasting in the relevant sitemap code again for easier reference:

    <map:serializers default="fo2pdf">
<map:serializer name="fo2pdf" src="org.apache.cocoon.blocks.fop.FOPNGSerializer" mime- type="application/pdf">
        <user-config>{lm:pdf.user-config}</user-config>
       </map:serializer>
    </map:serializers>

Sjur