Hi,
I think this maynot be theme related, but I have been told by my hosting provider to check with you.
When I upload anyfiles to the site they produce a 404 error, this is an example
Actual location of uploaded content
http://shop.morso.co.uk/wp-content/blogs.dir/4/files/2015/01/logo-150×90.jpg
Referenced location
http://shop.morso.co.uk/files/2015/01/logo-150×90.jpg
I think it’s a server issue, as seen here https://wordpress.org/support/topic/multisite-blogs-images-not-showing
My .htaccess file looks like this
# BEGIN WordPress
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ – [L]
# uploaded files
# RewriteRule ^files/(.+) wp-includes/ms-files.php?file=$1 [L]
RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^ – [L]
RewriteRule . index.php [L]
# END WordPress
Thanks
Ash