Chrome Debug: Cannot load http://localhost:[...] Connection refused

I've been using the Chrome Debug feature for a long time now to debug my Angular application, and it always worked great. Recently though, when I tried to debug, my breakpoints did not work. I went and set them in Chrome Dev Tools, which IntelliJ notices and tries to navigate to the code, which is when I get this message: 

Cannot load 'http://localhost:4200/filename.js': Connection refused (Connection refused)

Opening the URL in any browser (or fetching it with curl) works fine, so I don't think it's my network settings. Fiddling around with "Change HTTP Proxy settings" didn't help.

Is there anything I could try to fix this? It really hurts my ability to debug.