Oxygen insert row bug

doc.xml

<?xml version="1.0" encoding="UTF-8"?>
<book xmlns="http://docbook.org/ns/docbook" xmlns:xi="http://www.w3.org/2001/XInclude"
    xmlns:xlink="http://www.w3.org/1999/xlink" version="5.0" xml:id="sbook.lzc_22l_mbb">
    <info>
        <title>Foo</title>
    </info>
    
    <xi:include href="preface1.xml"/>
    <preface xml:id="asdf">
        <info>
        <title>A Second Preface</title>
        </info>
        <table frame="all" xml:id="table.srk_yx5_ncb">
            <title>adfsd</title>
            <tgroup cols="2">
                <colspec colname="c1" colnum="1" colwidth="1*"/>
                <colspec colname="c2" colnum="2" colwidth="1*"/>
                <thead>
                    <row>
                        <entry>sadf</entry>
                        <entry>sdaf</entry>
                    </row>
                </thead>
                <tbody>
                    <row>
                        <entry/>
                        <entry/>
                    </row>
                </tbody>
            </tgroup>
        </table>
    
    </preface>
</book>

Oxygen-Error-Dialog.png

preface1.xml

<?xml version="1.0" encoding="UTF-8"?>

<preface xml:id="soc-terminology" xmlns="http://docbook.org/ns/docbook"
    xmlns:fo="http://www.w3.org/1999/XSL/Format"
    xmlns:fox="http://xmlgraphics.apache.org/fop/extensions"
    xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xi="http://www.w3.org/2001/XInclude"
    xmlns:xs="http://www.w3.org/2001/XMLSchema" version="5.0">
    <title>Styles</title>
    <para>Blah blah.</para>
</preface>

1. Save doc.xml and preface1.xml on your file system.
2. Open doc.xml in Oxygen.
3. Put the cursor in an entry in the table.
4. Invoke an insert table row action (insert.table.row.above, insert.table.row.below, insert.table.rows.custom) using a toolbar button or the DocBook5->Table menu).

Expected behavior: A row or rows are inserted.
Actual behavior: The Error dialog shown in Oxygen-Error-Dialog.png appears.