Rails 4 image-path, image-url and asset-url no longer work in SCSS files

Question

I just had this issue myself.
3 points that will hopefully help:

If you place images in your app/assets/images directory, then you should be able to call the image directly with no prefix in the path. ie. image_url('logo.png')
Depending on where you use the asset will depend on the method. If you are using it as a background-image: property, then your line of code should be background-image: image-url('logo.png'). This works for both less and sass stylesheets. If you are using it inline in the view, then you will need to use the built in image_tag helper in rails to output your image. Once again, no prefixing <%= image_tag 'logo.png' %>
Lastly, if you are precompiling your assets, run rake assets:precompile to generate your assets, or rake assets:precompile RAILS_ENV=production for production, otherwise, your production environment will not have the fingerprinted assets when loading the page.

Also for those commands in point 3 you will need to prefix them with bundle exec if you are running bundler.