Customize Navigation AEM 6.3, downloads target url

Hi,

we have customized the Navigation to add new navigations. Below is the XML and this is placed under /apps/cq/core/content/nav/.content.xml path.

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

<jcr:root xmlns:sling="http://sling.apache.org/jcr/sling/1.0" xmlns:jcr="http://www.jcp.org/jcr/1.0"

          xmlns:nt="http://www.jcp.org/jcr/nt/1.0" jcr:primaryType="nt:unstructured">

    <mecimport

        jcr:mixinTypes="[rep:AccessControllable]"

        jcr:primaryType="nt:unstructured"

        jcr:title="Mec Import"

        sling:orderBefore="apps"

        id="cq-mecimport">

        <manual

            jcr:description="Manual Import"

            jcr:primaryType="nt:unstructured"

            jcr:title="Manual Import"

            href="/etc/aem-mec-import/importer.html"/>

        <report

            jcr:primaryType="nt:unstructured"

            jcr:title="Dashboard"

            href="/etc/aem-mec-import/index.html"/>

    </mecimport>

    <scaffolding

        jcr:mixinTypes="[rep:AccessControllable]"

        jcr:primaryType="nt:unstructured"

        jcr:title="Scaffolding"

        sling:orderBefore="apps"

        id="cq-scaffolding">

        <callback

            jcr:description="callback"

            jcr:primaryType="nt:unstructured"

            jcr:title="Callback"

            href="https://forums.adobe.com/etc/scaffolding/singtel/callback.html"

            target="_blank"/>

        <crossproductsell

            jcr:description="Cross Product Selling"

            jcr:primaryType="nt:unstructured"

            jcr:title="Cross Product selling"

            href="/etc/scaffolding/spring/crossproductsell.html"

            target="_blank"/>

        <decisiontree

            jcr:description="Decisiontree"

            jcr:primaryType="nt:unstructured"

            jcr:title="Decisiontree"

            href="/etc/scaffolding/spring/decisiontree.html"

            target="_blank"/>

    </scaffolding>

</jcr:root>

when we navigate to  links inside scaffolding, the target URL opens properly while when clicks on the links inside mecimport -> manual or mecimport-> report, this downloads the target i.e. /etc/aem-mec-import/importer.html & /etc/aem-mec-import/index.html

if i change these target urls /content/xxx/yyy/abc.html, it opens the page. Is there any limitation that we cannot put custom project path as target in navigation ?

Note :- aem-mec-import is of type sling:Folder and the htmls (/etc/aem-mec-import/importer.html & /etc/aem-mec-import/index.html) are nt:file

While this works perfectly fine on AEM 6.1. This issue happening when we upgraded to 6.3.

Please suggest.