Assets won't precompile when deploying with capistrano to production on amazon EC2

You don't need your own :precompile_assets task. You are using Capistrano's by including load 'deploy/assets' in your Capfile.

Removing the :precompile_assets task from your deploy.rb may resolve the issue. If you look at the source code for Capistrano, you'll see it implements :precompile_assets quite differently: https://github.com/capistrano/capistrano/blob/legacy-v2/lib/capistrano/recipes/deploy/assets.rb