bug? one-word table cell not appearing

In the following FO table, the word "Final" doesn't appear in the first
row.  Note that the first column contains only one word.

The word "Final" does appear in the second row. Note that the first
column contains more than one word.

Is this a bug, or is it just me? I'm using FOP 0.20.3 on Linux.

<?xml version="1.0" encoding="UTF-8"?>
<fo:root xmlns:fo="http://www.w3.org/1999/XSL/Format";>
<fo:layout-master-set>
<fo:simple-page-master margin-bottom="1cm" margin-top="1.5cm" 
margin-right="1cm" margin-left="1cm" page-width="21.5cm" page-height="27.9cm" 
master-name="mainPage">
<fo:region-before extent="1cm"/>
<fo:region-after extent="1cm"/>
<fo:region-body margin-bottom="1cm" margin-top="1cm"/>
</fo:simple-page-master>
</fo:layout-master-set>
<fo:page-sequence initial-page-number="1" master-reference="mainPage">

<fo:flow font-size="10pt" font-family="serif" flow-name="xsl-region-body">

<fo:table table-layout="fixed" space-after="0.5em" space-before="0.5em">
<fo:table-column column-width="12.675cm"/>
<fo:table-column column-width="3.9000000000000004cm"/>
<fo:table-body>
<fo:table-row>

<fo:table-cell>
<fo:block>
        <fo:block space-after="4pt" space-before="4pt">Review</fo:block>
</fo:block>
</fo:table-cell>
<fo:table-cell>
<fo:block>
<fo:block space-after="4pt" space-before="4pt">Final</fo:block>
</fo:block>
</fo:table-cell>
</fo:table-row>

<fo:table-row>


<fo:table-cell>
<fo:block>
        <fo:block space-after="4pt" space-before="4pt">Comprehensive 
Review</fo:block>
</fo:block>
</fo:table-cell>

<fo:table-cell>
<fo:block>
<fo:block space-after="4pt" space-before="4pt">Final</fo:block>
</fo:block>
</fo:table-cell>
</fo:table-row>
</fo:table-body>
</fo:table>

</fo:flow>
</fo:page-sequence>
</fo:root>
-- 
J. David Eisenberg  http://catcode.com/