In docbook-xsl-ns-1.78.1 (and going back to 1.77.1, I think), I've found
a possible bug in the sample webhelp/build.xml Ant file.
In the chunk target, the first xslt task, which generates a profiled
version of the document, specifies the Xerces XML parser:
<sysproperty key="org.apache.xerces.xni.parser.XMLParserConfiguration"
value="org.apache.xerces.parsers.XIncludeParserConfiguration"/>
A second xslt task processes the profiled document to generate the final
output, but it has no Xerces key. I find that this causes my olinks to
fail to resolve - haven't looked for any other side effects.
When I copied this sysproperty task to the second xslt task, the olinks
resolved.