Working through the Ruby on Rails Tutorial for Rails 4.0 and pushing to heroku after adding the bootstrap css and assets the css files were coming up blank.

Changing config.assets.compile to true in config/environments/production.rb seemed to fix the issue but I didn’t want to leave it configured this way.

Reverting this change and pushing to Heroku brought the behavior back. Running heroku run rake assets:precompile seems to fix the issue.

UPDATE: Seems this is only a temporary fix. According to this post it’s an issue with Heroku’s support of Rails 4.