Hello,
Thank you for contacting Rank Math support, and sorry for any inconvenience that might have been caused due to that.
I tried checking your sitemap on my end and it seems to be working just fine as you can see in my screenshot below:

Please follow the steps below:
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/
After that, check the sitemap again.
Let us know how that goes. Looking forward to helping you.
Hi,
Thank you for your reply.
So I did as you said and it comes up fine, though not in my GSC, I guess as it has not been updated yet.
Should I resubmit the sitemap or just leave it now?
Best
Ric
Hello,
You should remove all the sitemaps from the Search Console and submit sitemap_index.xml again and wait for Google to crawl the sitemap.
Hope this helps.
We look 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.