Load Balancer is listing status as Down.
In the load balancer portal, shows health checks at 100%.

On the server level, its receiving the health check requests, and returning 200 appropriately, what am I do doing wrong?

I have a similarly configured Load Balancer + upstream, and that seems to be working fine.

server {
        listen 50080 default_server;
        listen [::]:50080 default_server;

        server_name _;

        location / {
#               return 200;
        }
}

(https://imgur.com/a/oRQb3)