Search console error, blank line in sitemap.

That looks like a plugin or theme conflict. Can you try and gather as much information for us as possible? Please perform the following:
1. Check for conflicts.
2. Check for JavaScript errors with your console.
If you find any JavaScript errors related to Yoast SEO or if there is a conflict with a plugin or a theme, you can create a new GitHub issue for our developers. Please report the issue to a third party developer as well.
If you didn’t find any conflicts or errors, we think the issue is specific to your site. We’d need to investigate further but are unable to do so on these forums. You can purchase Yoast SEO Premium and receive our Premium email support and we can help you further.

Can you please try disabling and then re-enabling the sitemap feature, and then rechecking the page-sitemap? This will force a refresh of the sitemap. We have instructions on this here: https://kb.yoast.com/kb/enable-xml-sitemaps-in-the-wordpress-seo-plugin/

I tried to disable and then enable site map, but it wont fix the problem.

If disabling/enabling the sitemap did not resolve the issue, we suggest you proceed to do a conflict check.

Closed due to lack of activity.