Appian nginx Reverse Proxy - File Uploads Not Working

I am running Appian 17.1.1.0 behind an nginx instance running as a reverse proxy with the following configuration:

server {
    listen 80 default_server;
    server_name _;

    location / { 
        client_max_body_size 0;

        proxy_http_version 1.1;
        proxy_pass http://example.com:8080/;
        proxy_redirect http://example.com:8080/ http://$host/;

        proxy_set_header Accept-Encoding ""; 
        proxy_set_header Host $host; 
        proxy_set_header Origin example.com:8080;

        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Host $proxy_host;
        proxy_set_header X-Forwarded-Proto $scheme;
        proxy_set_header X-Forwarded-Server $host;
        proxy_set_header X-Real-IP $remote_addr;

        sub_filter_once off;
        sub_filter_types *;  
        sub_filter "example.com:8080" "$host";
    }

}

For ordinary perusing the invert intermediary works appian consummately, however when I attempt to transfer a record (e.g., changing the logo in the Appian Administration Console) the procedure turns always and doesn't appear to finish effectively. I have confirmed the transfer works accurately when not utilizing the intermediary.

In the wake of looking at the system movement utilizing the Firefox designer comfort it creates the impression that the document gets transferred, yet then the UI never refreshes and the page just continues sending AJAX calls to the backend server to keep an eye on the status of the record transfer. Anybody have any thoughts?