How do I get SignalR server deployed on AWS EKS behind nginx to allow websocket protocol connections?

Question

I have a .NET 6 Web API with SignalR. Everything works perfectly when connecting directly to the API - locally as well as via Endpoint IP:Port on AWS EKS. However, it's failing to connect specifically via the websocket transport method when I try to access it via the NGINX ingress URL (http://some.url.com). I get the following error:

Error: Failed to start the transport 'WebSockets': Error: WebSocket failed to connect. The connection could not be found on the server, either the endpoint may not be a SignalR endpoint, the connection ID is not present on the server, or there is a proxy blocking WebSockets. If you have multiple servers check that sticky sessions are enabled.

The fallback transports (Server Sent Events) work after the initial websocket try fails but I ideally want to connect via websocket.

I've tried enabling sticky sessions but that doesn't seem to make a difference, as well as suggestions from https://stackoverflow.com/questions/48300288/signalr-in-asp-net-core-behind-nginx - I get the exact same error.

This is what my Ingress looks like:

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: ingress-wsapp
  namespace: dev
  annotations:
    nginx.ingress.kubernetes.io/affinity: cookie
    nginx.ingress.kubernetes.io/read-timeout: '3600'
    nginx.ingress.kubernetes.io/send-timeout: '3600'
    nginx.ingress.kubernetes.io/configuration-snippet: |
      server {
        server_name some.url.com;

        location / {
          proxy_pass http://localhost:8081;
          proxy_http_version 1.1;
          proxy_set_header Upgrade $http_upgrade;
          proxy_set_header Connection $http_connection;
          proxy_set_header Host $host;
          proxy_cache_bypass $http_upgrade;
        }
      }
  namespace: dev
  labels:
    app: wsapp
spec:
  rules:
    - host: some.url.com
      http:
        paths:
        - path: /
          pathType: Prefix
          backend:
            service:
              name: wsapp
              port: 
                number: 8080