I know it's probably late, but here's an accurate and relevant answer your question - for the benefit of others who might be facing the same problem.

I recently - about a month back - bulk uploaded posts using the following template as provided by Blogging is Happiness at this link.

You may also check the full process at How to Bulk Import Posts into your Blogger blog using this free XML template.

<?xml version='1.0' encoding='UTF-8'?>
    <ns0:feed xmlns:ns0='http://www.w3.org/2005/Atom'>
    <ns0:title type='html'>Title</ns0:title>
    <ns0:generator>Blogger</ns0:generator>
    <ns0:updated>2025-04-27T23:16:25Z</ns0:updated>
    <ns0:entry>
        <ns0:category scheme='http://www.blogger.com/atom/ns#' term='Love'/>
        <ns0:category scheme='http://schemas.google.com/g/2005#kind' term='http://schemas.google.com/blogger/2008/kind#post' />
        <ns0:id>post-1</ns0:id>
        <ns0:author><ns0:name>Author</ns0:name></ns0:author>
        <ns0:content type='html'><a src="https://EverythingForBloggers.Blogspot.com">Blogging Is Happiness</a></ns0:content>
        <ns0:published>2025-04-28T23:16:25Z</ns0:published>
        <ns0:title type='html'>Everything For Bloggers</ns0:title>
    </ns0:entry>
</ns0:feed>