Thank you for contacting Rank Math support, and sorry for any inconvenience that might have been caused due to that.
We’ve checked your site, and couldn’t find any posts under those sitemaps.
Could you please confirm if the URLs are already set to index and published?
If so, please follow the steps in this link to flush your sitemap cache:
1. Flush the Sitemap cache by following this video screencast:
2. Exclude the Sitemap files of the Rank Math plugin in your caching plugin. The cache could be via a plugin or from the server. For plugins or Cloudflare, please follow this article:
Let us know how this goes.