My angular 7 apps sitemap.xml is not being picked up by webmaster tools

Question

My angular 7 apps sitemap.xml is not being picked up by webmaster tools

I have this sitemap.xml file (I've hidden real names):

<?xml version="1.0" encoding="UTF-8"?>
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://www.sitemaps.org/schemas/sitemap/0.9
            http://www.sitemaps.org/schemas/sitemap/0.9/sitemap.xsd">

  <url>
    <loc>https://mywebsite.co.uk/</loc>
    <lastmod>2018-11-28T13:11:30+00:00</lastmod>
  </url>

</urlset>

In webmaster tools I keep getting this error:

Your Sitemap appears to be an HTML page. Please use a supported sitemap format instead.

But my file is a .xml file. So I'm a bit confused.

Answer 1

How is this related to Angular? Is there HTML around the XML?

There should be XML only on https://mywebsite.co.uk/sitemap.xml

Copied Example from one of my sites:

<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
  <url>
    <loc>https://mywebsite.co.uk/</loc>
    <changefreq>weekly</changefreq>
    <priority>1</priority>
  </url>
</urlset>