Angular CLI hot module replacement not working

I am trying to set up an angular cli project with hot module replacement enabled. I followed the steps from https://github.com/angular/angular-cli/wiki/stories-configure-hmr however my application is still rebuilt completely each time some code changes.

For Example, I have a TestComponent that is declared by my TestModule. TestModule is imported by the AppModule. TestComponent looks like this:

<input type="text"/>

My AppComponent looks like this:

<input type="text"/>
<test-component></test-component>

Now, if I fill both input fields with some input and then make changes to TestComponent's code, with hmr enabled I would expect webpack to only rebuild the TestComponent, so that the input in AppComponent stays. However, the app is rebuilt entirely, the browser reloads and both inputs are gone. The console output states that webpack has detected changes and hmr will be executed.