Sitemap don’t work with a reverse proxy

I have a problem with the sitemap. I am using Rank Math version 1.0.218. And I have an nginx server behind an Nginx Proxy Manager.
I’ve added the code to my nginx configuration and followed all the steps in the documentation and the sitemap still doesn’t work.
Also, I couldn’t find any solution on the internet to configure it with a reverse proxy.

Here is the details of my environment:

• My sitemap URL is https://midri.net/sitemap_index.xml
• I’ve flushed the Rank Math cache multiple times according to your docs and still don’t work.
• I don’t have any WordPress plugin for cache.
• Also, I have added the rule on Cloudflare according to your docs

Here is what happens:

• When I try to open the sitemap page it redirects me to the home page (most of the times).
• However, on some occasions (I couldn’t reproduce when this happens), it downloads a sitemap_index.xml file with the same content as the WordPress index.php file. See the attached screenshot: https://imgur.com/a/iSCTXI7
• Tested in Google Chrome, Firefox, Edge and Brave browser and in all of them it redirect to the homepage.
• I’ve added the nginx configuration that you have in your documentation.
• I have a reverse proxy with Nginx Proxy Manager tool in docker.
• I have also tested this also in my local environment with the same configuration I have on production (docker, nginx proxy manger, etc) and the problem persist.

I don’t know what else I can do to solve this problem or know what is causing it.
I will appreciate if you help me with this,

Kind regards.