Missing XML tag in the Sitemap

Some posts on my blog were somehow non-indexed at Google search console, has it something to do with enabling the LOADING GOOGLE FONTS LOCALLY option? To solve it, I resubmitted my sitemap generated by my SEO plugin(showing all the posts) again but the next day I found following message in the Google search console-

The sitemap can be read but has errors

Missing XML tag This required tag is missing. Please add it and resubmit. 1 instance Line 10 Parent tag: urlset Tag: url`

Now, what needs to be done?