Error minifying CSS with django-require

[shelldweller]

When running ./manage collectstatic with django-require getting this error:

Post-processing 'mediabrowser/css/smoothness/jquery-ui-1.10.3.custom.min.css' failed!
...
ValueError: The file 'mediabrowser/css/smoothness/images/animated-overlay.gif' could not be found with <require.storage.OptimizedManifestStaticFilesStorage object at 0x7fbb7a356450>.