generate.citerefentry.link customization not emitting refentrytitle contents in XSL-NS stylesheets

I've got a Docbook 5 <refentry> page including

            <citerefentry><refentrytitle>glDepthRange</refentrytitle></citerefentry>

    and a stylesheet customization of ...xsl-ns/current/xhtml5/onechunk.xsl
including

    <xsl:param name="citerefentry.link" select="'1'"></xsl:param>
    <xsl:template name="generate.citerefentry.link"><xsl:value-of select="refentrytitle"/><xsl:text>.xhtml</xsl:text></xsl:template>

    When I process this with e.g.

xsltproc testref.xsl testref.xml

the generate.citerefentry.link template is run, but does not emit the
<refentrytitle> contents in testref.xhtml. I expect to see

<a class="citerefentry" href="glDepthRange.xhtml"><span class="citerefentry"><span class="refentrytitle">glDepthRange</span></span></a>

but in fact get

...href=".xhtml"...

    Did something change about the way this template should be coded between
the XSL and XSL-NS stylesheets? When I change the stylesheet in testref.xsl to
the old ...release/xsl/current/xhtml5/onechunk.xsl, the generated link
comes out correctly. This is using the the 1.78.1 releases of both XSL and
XSL-NS, as packaged by Debian.
    Thanks,
    Jon Leech