Assetic:dump on AWS

I'm trying to deploy my Symfony2 app on AWS Beanstalk. I've managed to get almost everything working except for dumping assets. The eb provisioning script runs fine, but the files are not present when I ssh into the ec2 instance. Here is the deployment log:

2015-01-21 14:12:34,414 [DEBUG] Running command 05_update_assets
2015-01-21 14:12:34,414 [DEBUG] Generating defaults for command 05_update_assets <<<

2015-01-21 14:12:35,027 [DEBUG] No test for command 05_update_assets
2015-01-21 14:12:37,870 [INFO] Command 05_update_assets succeeded
2015-01-21 14:12:37,871 [DEBUG] Command 05_update_assets output: Dumping all dev assets.
Debug mode is off.

14:12:36 [file+] /var/app/current/app/../web/css/2f21d5e.css
14:12:36 [file+] /var/app/current/app/../web/js/b21b935.js
14:12:36 [file+] /var/app/current/app/../web/js/2031a90.js
14:12:36 [file+] /var/app/current/app/../web/css/92da39d.css
14:12:36 [file+] /var/app/current/app/../web/css/b5828a3.css
14:12:37 [file+] /var/app/current/app/../web/js/31db152.js

Any ideas what could cause this?