RewriteRule for .htaccess for uploaded files in a child site?

Images are broken within the WP Media Gallery. All other data seems to be working fine. I can only see an uploaded image when i go to “edit” an image within the Media Gallery image editor, other than that it is only broken file placeholders.

I believe it is an .htaccess problem.

Example:

File path:
/var/www/wordpress/wp-content/blogs.dir/4/files/2013/01/image.png

URL path:
https://domain.com/test3/files/2013/01/image.png (gives a 404)

Current rule in my .htaccess:

RewriteRule ^([_0-9a-zA-Z-]+/)?files/(.+)wp-includes/ms-files.php?file=$2 [L]

Does anybody know what this should be?

More Info:
Fresh WordPress 3.5.1 from the admin panel
All plug-ins deactivated
Files upload fine, just can’t see them via a browser
File permissions right now on all folders and files:: 775
Default Twenty Twelve theme
Only 1 child site in my network
Media Gallery seems to work fine in the main site, just not the child site.

Thanks everyone, any help or advice is really appreciated.