CORS issue with Nginx proxy server?

Question

I am trying to call a API that is on a docker container on port 80. I have set up a Nginx proxy server.

if i access via postman it works, so i assume the proxy server is set up correctly.

When I try to access via angular/$http I get the dreaded Access to XMLHttpRequest at 'http://mydomain:8099/api/v4/documents' from origin 'http://localhost:8080' has been blocked by CORS policy: Request header field x-session-token is not allowed by Access-Control-Allow-Headers in preflight response.

this is my Nginx default config file:

server {
    listen 8099 default_server;
    listen [::]:8099 default_server;

    location / {
         if ($request_method = 'OPTIONS') {
            add_header 'Access-Control-Allow-Origin' '*';
            add_header 'Access-Control-Allow-Credentials' 'true';
            add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS';
            add_header 'Access-Control-Allow-Headers' 'DNT,X-CustomHeader,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type';
            add_header 'Access-Control-Max-Age' 1728000;
            add_header 'Content-Type' 'text/plain charset=UTF-8';
            add_header 'Content-Length' 0;
            return 204;
         }
         if ($request_method = 'POST') {
            add_header 'Access-Control-Allow-Origin' '*';
            add_header 'Access-Control-Allow-Credentials' 'true';
            add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS';
            add_header 'Access-Control-Allow-Headers' 'DNT,X-CustomHeader,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type';
         }
         if ($request_method = 'GET') {
            add_header 'Access-Control-Allow-Origin' '*';
            add_header 'Access-Control-Allow-Credentials' 'true';
            add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS';
            add_header 'Access-Control-Allow-Headers' 'DNT,X-CustomHeader,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type';
         }

        proxy_pass       http://127.0.0.1;
        proxy_set_header Host      $host:$server_port;
        proxy_set_header X-Real-IP $remote_addr;

    }

}

Thanks for any help