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.
If it is empty, then it wouldn’t be generated or included in your sitemap index.
Could you please share the actual sitemap URL so we can check?
You can add it to the sensitive data section by editing your first post

It is completely secure, and only our support staff has access to that section.
Looking forward to helping you.
Hello,
I have updated the sensitive data as requested. Can you please check further?
Thank you.
Hello,
Please ensure that you are using the latest version of Rank Math plugin. If not yet, please do update them. You may refer to our changelog page here: https://rankmath.com/changelog/
We might also need to take a closer look at the settings. Please edit the first post on this ticket and include your WordPress & FTP logins in the designated Sensitive Data section.
Please do take a complete backup of your website before sharing the information with us.

It is completely secure and only our support staff has access to that section. If you want, you can use the below plugin to generate a temporary login URL to your website and share that with us instead:
https://wordpress.org/plugins/temporary-login-without-password/
You can use the above plugin in conjunction with the WP Security Audit Log to monitor what changes our staff might make on your website (if any):
https://wordpress.org/plugins/wp-security-audit-log/
We really look forward to helping you.