nginx-proxy-manager nginxproxymanager timing out 30s after POST request

Checklist

Have you pulled and found the error with jc21/nginx-proxy-manager:latest docker image?
- Yes
Are you sure you're not using someone else's docker image?
- Yes
Have you searched for similar issues (both open and closed)?
- Yes

Describe the bug

Have a dockerised Python app behind npm. The app has a feature for uploading a CSV file, which is then processed against an API endpoint. This takes quite a while and the result can be a bit big. I've set up the following in advanced:

proxy_connect_timeout  6000s;
proxy_read_timeout  6000s;
proxy_send_timeout  6000s;
send_timeout  6000s;
proxy_buffer_size 128k;
proxy_buffers 4 128k;
proxy_busy_buffers_size 128k;

No matter what I do I'm getting an Internal Service Error exactly after 30s leading me to believe that npm is not waiting for the reply from the host.

Nginx access log for proxied host [08/Oct/2024:06:09:58 +0000] - 500 500 - POST https domain.url "/bulk" [Client ip.ip.ip.ip] [Length 141] [Gzip -] [Sent-to ip.ip.ip.ip] "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/129.0.0.0 Safari/537.36" "https://domain.url/bulk"

The function runs properly when accessing the docker image directly (on the exposed port).

Nginx Proxy Manager Version

To Reproduce N/A

Expected behavior

NPM to properly wait for the response to serve it back to the requestor

Screenshots