Harvard Referencing Style missing from Word 2019

Hi there,

I am having an issue with the Referencing options on Word 2019. 

Harvard referencing was available on my styles dropdown last time I needed it -  about a year ago. It has now disappeared from the option list. MLA and APA are available but not Harvard

When I opened a document that I had written when Harvard was an available option, I clicked on my references list and got an error that said 

'You do not have the bibliography style that is currently being used in this document. Completing this action will reformat the bibliography and citations to your default bibliography style.;

When I look in C:\Users\name\AppData\Roaming\Microsoft\Bibliography\Style the Harvard XSL Stylesheet is there under HarvardAnglia2008OfficeOnline

When I open the Stylesheet online I am shown this:

This XML file does not appear to have any style information associated with it. The document tree is shown below.
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:msxsl="urn:schemas-microsoft-com:xslt" xmlns:b="http://schemas.openxmlformats.org/officeDocument/2006/bibliography" xmlns:t="http://www.microsoft.com/temp" version="1.0">
<xsl:output method="html" encoding="us-ascii"/>
<xsl:template match="/">
<xsl:call-template name="Start"/>
</xsl:template>
<xsl:template name="Start">
<xsl:choose>
<xsl:when test="b:Version">
<xsl:text>2010.2.02</xsl:text>
</xsl:when>
<xsl:when test="b:XslVersion">
<xsl:text>2008</xsl:text>
</xsl:when>
<xsl:when test="b:StyleNameLocalized">
<xsl:choose>
<xsl:when test="b:StyleNameLocalized/b:Lcid='1033'">
<xsl:text>Harvard - Anglia</xsl:text>
</xsl:when>

It continues and ends with </xsl:stylesheet>

Please help, I have a thesis due in May and my university insists on Harvard referencing. 

Thank you

Sarah