Disable Featured image in WordPress Network Websites
No Featured Image: Here’s a gotcha for anyone getting to grips with Networked WordPress sites (what used to be known as WordPress MU prior to 3.1).
Normally you would enable Featured Images by adding the following to your functions.php file in your theme folder;
if (function_exists('add_theme_support')) { add_theme_support( 'post-thumbnails'); }
However if you are running networked sites this won’t work….unless you have already authorised image upload in the Network settings. Change view to ‘Network Admin’ and then select the Settings -> Network Settings option. In your ‘Upload Settings’ section, ensure that image upload is enabled.
You’re back in business.
Thanks to Andrea R for posting this solution on the WP support forum.
http://wordpress.org/support/topic/no-featured-image-metabox-in-mu