I am trying to filter out subtrees using element namespaces.

    <xsl:template match="EMPLOYEES">
        <xsl:apply-templates  select="NAME[namespace-uri()='http://www....

<EMPLOYEE xmlns="http://www.monday.com/">

You try to match NAME elements, but the actual elements are apparently
EMPLOYEE elements.

Using
 <xsl:apply-templates select="EMPLOYEE[namespace-uri()='http://www....
or
 <xsl:apply-templates  select="*[namespace-uri()='http://www....
will get you closer to your goal.