(Chrome/IE) 502.3 error encountered when POST-ing a file to an SSL-enabled IIS server running ARR that routes to JBoss

Question

I am trying to get a file upload function to work on my site. It basically POSTs an image + image_id to the server.

The server is running IIS7 with ARR. I have JBoss AS 7 running in the server as well, but have opted to route requests to it using IIS. I have SSL set up on both IIS and JBoss and use ARR to do the routing. This is my setup:

1. POST the image + image_id to https://hello.example.com/upload-image
2. A dummy IIS site is set up with SSL to handle https://hello.example.com, it just allows the request to pass through.
3. I have configured a server farm in ARR that points to my JBoss server.
4. I configure a URL rewrite rule that routes *hello.example.com* requests to https://{jboss-server}/{R:0}

Everything works fine until I decide to upload an image. When I do I get a 502 Bad Gateway error (502.3 timeout, specifically). If I modify the request and only POST the image_id, it doesn't cause this error.

Now, I suspect it might be the SSL that's messing up stuff, so I modified my IIS site and the ARR routing rule to just use http... lo and behold, I am able to upload the image.

Oh, and it works fine in Firefox BUT not Chrome/Safari/IE!

Has anyone encountered this issue? How can I debug this more effectively?