Page numbering not correct with more than 10 items in menu

With the following menus in my navigation.xml file:

<menu name="User Guide">
<item name="Home" href="/index.html"/>
<item name="Introduction" href="/intro.html"/>
<item name="Installation" href="/install.html"/>
<item name="Screen Elements" href="/screen.html"/>
<item name="Usage" href="/usage.html"/>
<item name="Known Problems" href="/problems.html"/>
<item name="Documentation" href="/doc.html"/>
<item name="History" href="/history.html"/>
<item name="Credits" href="/credits.html"/>
<item name="Style Files" href="/style.html"/>
<item name="License" href="/license.html"/>
</menu>
<menu name="Appendix">
<item name="Bibliography" href="/bib.html"/>
</menu>

the page number of the pdf file gets reset to one at the 11th section ("License"). Interestingly, if I move 10 items from the first into the second menu, the page numbering stays correct, so it only seems to affect the first menu.