DITA keydef conkeyref not working in HTML5

I am trying to use keydef/conkeyref s to improve my re-use of content and reduce errors.

I am applying it a similar fashion to what is described here.

The published content and conkeyrefs are working well when I publish in PDF format but not in responsive HTML5.  For keywords both worked fine.

The ditamap was as follows;

<map xmlns:ditaarch="http://dita.oasis-open.org/architecture/2005/">
<title>Test MAP</title>
<keydef keys="product_title"><!-- product_version = "1.5.20"-->
<topicmeta>
<keywords>
<keyword>RAPTOR
- Quick Start Guide</keyword>
</keywords>
</topicmeta>
</keydef>
<keydef keys="product_version"><!-- product_version = "1.5.20"-->
<topicmeta>
<keywords>
<keyword>1.5.04</keyword>
</keywords>
</topicmeta>
</keydef>
<keydef keys="product_date"><!-- product_version = "1.5.20"-->
<topicmeta>
<keywords>
<keyword>December
2020</keyword>
</keywords>
</topicmeta>
</keydef>
<keydef href="../../graphics-warehouse.xml" keys="graphics"
type="concept">
<topicmeta>
<navtitle>Graphics Reference Warehouse</navtitle>
</topicmeta>
</keydef>
<keydef href="../../warehouse.xml" keys="corporate" type="concept">
<topicmeta>
<navtitle>Warehouse</navtitle>
</topicmeta>
</keydef>
<topicref href="../../book_common/Frontmatter/title_page_template.xml"
type="concept"></topicref>
<topicref href="../../book_common/Frontmatter/Copyright_Contact.xml"
type="concept">
<topicmeta>
<navtitle>Copyright Notice</navtitle>
</topicmeta>
</topicref>
</map>

Warehouse.xml is as follows:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE concept PUBLIC "-//OASIS//DTD DITA 1.3 Concept//EN" "technicalContent/dtd/concept.dtd" [
]>

<concept id="id20CIDF00UHT">
<title>Warehouse</title>
<shortdesc>This is the warehouse of terms used by the iMX350 documents</shortdesc>
<prolog>
<author></author>
</prolog>
<conbody>
<p id="copyright">© 2021 iS5 Communications Inc. All
rights reserved.</p>
</conbody>
</concept>

The reference to the copyright key in "../../book_common/Frontmatter/Copyright_Contact.xml" is as follows:  <p conkeyref="corporate/copyright">© 2020 iS5 Communications Inc. All rights reserved.</p>

As mentioned above, when I publish in PDF this copyright message is overwritten to "© 2021 iS5 Communications Inc. All rights reserved.".  When I publish in HTML5 it is left unchanged.

Is this a bug?  I am using the 2019 Framemaker