Ember broccoli compilation working on windows but not on OSX

I have an ember app that uses ember-cli-compass-compiler to compiles scss files. It works fine on my windows environment but I am running into problems on OSX.

When I run ember serve, I can see compass_compiler_output_path folders being created in the tmp folder, and the compiled css files are in there, but when I open the website I am greeted with a error 404 for file http://localhost:4200/assets/app.css

Any ideas on how to identify the problem? Is it ember that decides what gets hosted on the web server? or broccoli? and why is it working on one env but not the other.