Hello,
Thank you for contacting Rank Math and bringing your concern to our attention. I’m sorry for any inconvenience this issue may have caused you.
I’ve checked some of your posts and pages from your sitemap, and they are already indexed.
Each time Google uses a sitemap to find a URL, the count of the Discovered URLs increases by one. When the count of the Discovered URLs is zero or does not match your actual sitemap, it means Google didn’t use the sitemap to find the URLs.
Here’s a link for more information:
https://rankmath.com/kb/zero-discovered-urls-through-sitemap/
Please note that if the URLs are getting discovered by other means, then the discovered URLs in the sitemap section can be zero. It mostly happens when you have good internal linking or use the Instant Indexing plugin. Can you please confirm if that’s the case on your site?
Looking forward to helping you.
Thank you.
		
	 
	
	
	
	
 
			
				
	
	
		
		Yeah i have seen some pages are discovered by other means. But some pages are indexed but it is not indicated whether they were discovered by sitemap or refering page. It just indicates, 
Sitemaps – No referring sitemaps detected
Referring page- None detected
URL might be known from other sources that are currently not reported
Can that be a problem?
		
	 
	
	
	
	
 
			
				
	
	
		
		Hello,
It is fine to have a URL reported with “No referring sitemaps detected”. If Google discovers the URL through other means, it may not cross reference your sitemap to check if the URL is there. Hence the “No referring sitemaps” message.
As long as your sitemap is valid and URLs from your website are being discovered, you can ignore the “No referring sitemaps detected” message.
Hope that helps. Please let us know if you have questions.
		
	 
	
	
	
	
 
			
				
	
	
		
		Hello,
We are super happy that this resolved your issue. If you have any other questions in the future, know that we are here to help you.
If you don’t mind me asking, could you please leave us a review (if you haven’t already) on https://wordpress.org/support/plugin/seo-by-rank-math/reviews/#new-post about your overall experience with Rank Math? We appreciate your time and patience.
If you do have another question in the future, please feel free to create a new forum topic, and it will be our pleasure to assist you again.
Thank you.