xref to mediaobject or imageobject doesn't work

Hi,
if I have <sect id="x1" xreflabel="label1"> and
<xref linkend="x1"> I got in the pdf a link label1.
If I click on it the reader jumps to the section.

But if I try it with <mediaobject id="x2" xreflabel="label2">
and <xref linkend="x2"> I got only the link but can't jump.

And docbook-xsl 1.65.1 produces:
sect: <fo:basic-link internal-destination="x1">section 3.3, 
&#8222;label1&#8220;</fo:basic-link>

and

to pic: <fo:basic-link internal-destination="x2">label2</fo:basic-link>

But if I search for <fo:block id=" I only find x1 and not x2 ...

A bug of docbook-xsl 1.65.1

wkr Thomas