Hello,
Thank you for contacting Rank Math support, and sorry for any inconvenience that might have been caused due to that.
Checking your sitemap on our end, it seems to be loading just fine. See the screenshot below for reference:

Please follow the steps below and see if this will improve your situation:
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/
If the issue persists, please share a screenshot of the issue from your end.
Looking forward to helping you.
Hello,
Since we did not hear back from you for 15 days, we are assuming that you found the solution. We are closing this support ticket.
If you still need assistance or any other help, please feel free to open a new support ticket, and we will be more than happy to assist.
Thank you.