Hello,
Thanks for contacting us and sorry for any inconvenience that might have been caused due to that.
I can check that your site has a total of 19 posts and your post sitemap already includes all of them:

And your posts sitemap is accessible at https://www.healthideabd.xyz/post-sitemap.xml since you are using the WWW version of your site. However, the non-WWW version of the sitemap should redirect to the WWW version but it isn’t. Please follow this guide to fix the issue: https://rankmath.com/kb/couldnt-fetch-error-google-search-console/#num-5-4-redirect-all-three-other-versions-to-your-preferred-variation
Hope this helps.
Hello,
Can you please follow these steps?
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/
That should fix the issue. Please let me know if that does not. We are here to assist.
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.