Saxon

I used a predicate pb[position() mod 2 = 1] in the group-starting-with pattern of an xsl:for-each-group and with Saxon 9.9.1.5 EE that seems to pass the streamability analysis but then fails on execution with

Using parser com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl$JAXPSAXParser
java.lang.UnsupportedOperationException: net.sf.saxon.trans.XPathException: Navigation using preceding-sibling axis is not supported from a streamed input node
        at com.saxonica.ee.stream.om.FleetingNode.iterateAxis(FleetingNode.java:512)
        at com.saxonica.ee.stream.om.FleetingElementNode.iterateAxis(FleetingElementNode.java:98)
        at net.sf.saxon.tree.util.Navigator.getSiblingPosition(Navigator.java:1136)
        at net.sf.saxon.pattern.GeneralPositionalPattern.getActualPosition(GeneralPositionalPattern.java:273)
        at net.sf.saxon.pattern.GeneralPositionalPattern.internalMatches(GeneralPositionalPattern.java:242)
        at net.sf.saxon.pattern.GeneralPositionalPattern.matchesBeneathAnchor(GeneralPositionalPattern.java:222)
        at net.sf.saxon.pattern.GeneralPositionalPattern.matches(GeneralPositionalPattern.java:207)
        at com.saxonica.ee.stream.adjunct.GroupStartingTester.notifyItem(GroupStartingTester.java:35)
        at com.saxonica.ee.stream.watch.ForEachGroupPartitionAction.startSelectedParentNode(ForEachGroupPartitionAction.java:123)
        at com.saxonica.ee.stream.watch.Trigger.startSelectedParentNode(Trigger.java:85)
        at com.saxonica.ee.stream.watch.WatchManager.startElement(WatchManager.java:274)
        at net.sf.saxon.event.StartTagBuffer.startContent(StartTagBuffer.java:246)
        at com.saxonica.ee.stream.ContentDetector.flush(ContentDetector.java:97)
        at com.saxonica.ee.stream.ContentDetector.endElement(ContentDetector.java:55)
        at net.sf.saxon.event.ReceivingContentHandler.endElement(ReceivingContentHandler.java:528)
        at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.endElement(Unknown Source)
        at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanEndElement(Unknown Source)
        at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl$FragmentContentDriver.next(Unknown Source)
        at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(Unknown Source)
        at com.sun.org.apache.xerces.internal.impl.XMLNSDocumentScannerImpl.next(Unknown Source)
        at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanDocument(Unknown Source)
        at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(Unknown Source)
        at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(Unknown Source)
        at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(Unknown Source)
        at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.parse(Unknown Source)
        at com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl$JAXPSAXParser.parse(Unknown Source)
        at net.sf.saxon.event.Sender.sendSAXSource(Sender.java:435)
        at net.sf.saxon.event.Sender.send(Sender.java:167)
        at net.sf.saxon.trans.XsltController.applyStreamingTemplates(XsltController.java:1050)
        at net.sf.saxon.s9api.AbstractXsltTransformer.applyTemplatesToSource(AbstractXsltTransformer.java:339)
        at net.sf.saxon.s9api.Xslt30Transformer.applyTemplates(Xslt30Transformer.java:311)
        at net.sf.saxon.Transform.processFile(Transform.java:1283)
        at net.sf.saxon.Transform.doTransform(Transform.java:815)
        at net.sf.saxon.Transform.main(Transform.java:80)
Caused by: net.sf.saxon.trans.XPathException: Navigation using preceding-sibling axis is not supported from a streamed input node
        at com.saxonica.ee.stream.om.FleetingNode.iterateAxis(FleetingNode.java:509)
        ... 33 more
Fatal error during transformation: java.lang.UnsupportedOperationException: net.sf.saxon.trans.XPathException: Navigation using preceding-sibling axis is not supported from a streamed input node

Complete code is

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
    xmlns:xs="http://www.w3.org/2001/XMLSchema"
    xpath-default-namespace="http://www.tei-c.org/ns/1.0"
    exclude-result-prefixes="#all"
    version="3.0">
    
    <xsl:mode on-no-match="shallow-copy" streamable="yes"/>
    
    <xsl:output method="html" indent="yes" html-version="5"/>
    
    <xsl:template match="/">
        <html>
            <head>
                <title>.NET XSLT Fiddle Example</title>
            </head>
            <body>
                <xsl:apply-templates select="TEI/text/body"/>
            </body>
        </html>
    </xsl:template>
    
    <xsl:template match="body">
        <div class="panel-body">
            <xsl:for-each-group select="*" group-starting-with="pb[position() mod 2 = 1]">
                <div style="display: flex; flex-direction: row;">
                    <xsl:for-each-group select="current-group()" group-starting-with="pb">
                        <div style="border: solid 1px red;">
                            <xsl:apply-templates select="current-group()"/>
                        </div>
                    </xsl:for-each-group>
                </div>
            </xsl:for-each-group>
        </div>
    </xsl:template>
    
    <xsl:template match="pb">
        <div class="page number" style="text-align:right;">
            <xsl:text>[F.</xsl:text>
            <xsl:value-of select="@n"/>
            <xsl:text>]</xsl:text>
            <hr/>
        </div>
    </xsl:template>
    
    <xsl:template match="p">
        <p>
            <xsl:apply-templates/>
        </p>
    </xsl:template>
    
</xsl:stylesheet>

Sample input is:

<TEI xmlns="http://www.tei-c.org/ns/1.0">
    <teiHeader>
        <fileDesc>
            <titleStmt>
                <title>Test</title>
                <author>John Doe</author>
            </titleStmt>
        </fileDesc>
    </teiHeader>
    <text>
        <body>
            <pb n="1"></pb>
            <p> Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet. Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet. </p>
            <pb n="2"></pb>
            <p>Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet. Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet. </p>
            <pb n="3"></pb>
            <p> Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet. Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet. </p>
            <pb n="4"></pb>
            <p>Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet. Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet. </p>
            <pb n="5"></pb>
            <p> Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet. Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet. </p>
            <pb n="6"></pb>
            <p>Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet. Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet. </p>
            <pb n="7"></pb>
            <p> Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet. Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet. </p>
            <pb n="8"></pb>
            <p>Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet. Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet. </p>
        </body>
    </text>
</TEI>

I guess the positional predicate in the pattern should be rejected by the streamability analysis.