Couldn't Fetch XML Sitemap

We have around 23 subdomains with dynamically generated sitemaps for each subdomains.

Google is fetching all the sitemap in search console except one subdomain irrespective of the fact that everything is quite similar in terms of coding and structure.

I have tried every possible method but that one subdomain's xml sitemap isn't read by Google. It has been around 2 months that Google haven't read the sitemap.

Please let me know any solution to fix this.

you can submit all url on google doc file then submit and share google doc file on web 2.0 then you can get positive result

Generate sitemap and upload it again and generate file in doc format may be this will help you.