Iis – IE does not properly use it’s local cache for intranet sites and returns HTTP 200 instead of HTTP 304

I am a developer facing a problem at work. When I create any kind of .Net web application (ASP.Net, ASP.Net MVC), deploy it on my local machine's IIS or as an intranet application on our intranet IIS server and run it in a browser I get an unexpected result in IE.

Normally when you first access a site the files are downloaded and stored in the browser's local cache. On subsequent visits the browser sends a request to the server with the files Etags or last modified date. The server can respond with HTTP 304 if the files haven't changed thus preventing a full transfer of the file.

On my work network this works as expected for all browsers except IE who always returns HTTP 200 and thus downloads the file again.

I can start a new project in Visual Studio and caching works fine for other browsers but not IE. If I create the same project at home (on my own computer), caching works fine for all browsers including IE.

This makes me believe that there is something interfering with the process. Possibly some IE configuration (which is controlled by a Group Policy which I do not have access or maybe an IIS configuration, which again I do not have access or something else entirely.

I have access to IE's temporary files and I can see that the files are present in this folder.

What could be causing this? I need some information before approaching the sysadmins.

Headers under Fiddler

Developer Tools Network tab

EDIT:

Here is a new project that I created and hosted in Visual Studio's IIS Express:

IE First Load:

Firefox First Load:

IE Second Load:

As we can see all the requests are 200 and the total time is sensibly the same.

Firefox Second Load:

As we can see, all requests after the main one are 304 and the total time is less than half of the first load.