Using Ubuntu 14.04 64-bit with Nvidia 331.38 proprietary and tested drivers. Recently the icons in the launcher have no longer got any background color. There are also differences to the indication of how many windows are open of one application. This happened without warning or errors, modifications or tweaks on startup an ordinary day. Have absolutely no idea what additional information I can give you, want to know something use the comments.
I've tried the following things: Resetting Unity in every way possible, I've resetted all settings all icon themes all settings (you see numix in the screenshot cause why not). I've also changed drivers multiple times. And yes, I've restarted my computer... And Unity :)
Previous post with similar issues, no solution that works: post
Update: As I entered the settings for Ubuntu I discovered that parently many of the default unity elements had no background either. See image #2.