First, check your news sitemap in an online XML validator like https://www.xml-sitemaps.com/validate-xml-sitemap.html
It may already provide you with some clues about what could be going wrong. If there are errors reported that you do not understand or know how to fix, you can ask public support on https://wordpress.org/support/plugin/xml-sitemap-feed/.
If you’re a Google News Advanced user with an active license, get priority support on our Support Forum or Your account (after login) or create a support ticket via Priority support (provide your license key).
Then, make sure the Publication name matches. Google News does not always clearly specify what the problem is. So even if it does not say the publication name is not found, it may still be an issue.
Read more on how to verify and fix that on Publication name does not match…
Lastly, get support.
You can ask public support on https://wordpress.org/support/plugin/xml-sitemap-feed/ or https://support.google.com/googlenews/community