When I log into the wp-admin dashboard all the icons are missing. Most of them are replaced with a empty square or just a blank spot.

Background:

I've duplicated my WordPress website on two servers - beta and live. On live everything works fine. On beta when I log into the wp-admin dashboard all the icons are missing. To test further I setup a local version of the site on my laptop. The icons appear as normal here.

On my beta server I checked directory permissions, made sure the DB was the same as the live DB ( used a live DB dump ), checked the logs, and also deactivated all plugins. The icons are always missing and there are no obvious or useful error messages being throw.

Update: The only thing that seems to fix it is this. If I enable SCRIPT_DEBUG in the config ( to not use minified JS ) - it seems to work.

Picture of dashboard missing icons .jpg

Picture of dashboard with working icons .jpg