Thank you for contacting Rank Math support. We can check that your sitemap is working fine.

Please confirm if you have resolved the issue or need any further assistance with this.

Looking forward to helping you.

i have tried every possible method to fix the issue but no result.

1. Flush the Sitemap cache by following this video screencast:
   https://i.rankmath.com/pipRDp
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:
   https://rankmath.com/kb/exclude-sitemaps-from-caching/
3. Apply the following filter code to your site.
   add_filter( 'rank_math/sitemap/enable_caching', '__return_false');

Here’s how you can add filter to your WordPress site:https://rankmath.com/kb/wordpress-hooks-actions-filters/

Let us know how that goes. Looking forward to helping you.