Sitemap 404 error for nginx server

I’m getting a 404 error when clicking on the /sitemap.xml link from SmartCrawl. I checked it and I can see that the sitemap has been properly created and that it’s placed under /wp-content/uploads/sitemap.xml instead of being in /sitemap.xml

I’ve found this ticket https://premium.wpmudev.org/forums/topic/smartcrawl-sitemap-404-error on which a fix is suggested consisting in adding a line to nginx.conf file, but I would rather prefer not to have to edit the file. From what I see, your plugin should work without custom NGINX rules.

t works fine on other sites which use NGINX. We need to find out why it's not working. This website uses Nginx as a reverse proxy to Apache with htaccess enabled.

Can you please help me understand why it's not working?