If you're deploying via the engineyard CLI, please try updating it via "gem update engineyard". It sounds like your local version of the CLI isn't in step with engineyard-serverside, and that could prevent the assets from being compiled properly on deploy.
Other things to check:
- Is the environment you're deploying to fully upgraded?
- Does assets.enabled or assets.disabled show up anywhere else in your application? (grep -ir 'assets.enabled' /path/to/app; grep -ir 'assets.disabled' /path/to/app)
- After the deploy, is /data/appname/current/public/assets a valid symlink to /data/appname/shared/assets? Is anything in there?
- What's your disk space usage look like (df -h)? Is /data anywhere near full?
- Try deploying through the dashboard - do you get the same result?
- If you look at your deploy logs (/home/deploy/appname-deploy.log), do you see output there that mimics what's in engineyard-serverside's "app_needs_assets?" method you linked above? "~> app/assets/ found. Attempting Rails asset pre-compilation.", "~> public/assets already exists, skipping pre-compilation.", or "~> application.rb has disabled asset compilation. Skipping."?
If none of these tips are helpful, please open a ticket with Application Support so we can take a closer look at your application/environment and attempt to reproduce the issue.