As we use Cloudflare to protect our services the user's IP Address is sent in a different header, due to this you will need to update Umbraco Forms to use a different header.
You can use the following Magic String:
[@CF-Connecting-IP]
If you need to set this on a global level we recommend using the ASP.NET's forwarded header middleware:
https://learn.microsoft.com/en-us/aspnet/core/host-and-deploy/proxy-load-balancer
You can find a list of the headers used by Cloudflare here:
https://developers.cloudflare.com/fundamentals/reference/http-request-headers/
