[SmartCrawl Pro] Google cannot read sitemap.xml

Google console gives me an Analysis Error "Google cannot read sitemap.xml". I consulted it online with your stuff, once it was OK, but then again no. It can be related to Hummingbird.

This tools gives me an error about Incorrect http header content type.
https://www.xml-sitemaps.com/validate-xml-sitemap.html?op=validate-xml-sitemap&go=1&sitemapurl=https%3A%2F%2Fwww.fenixnaradi.cz%2Fsitemap.xml&submit=Validate+Sitemap