I had a look into the issue and was rather suprised it even exists. We have not changed anything on the Character Builder besides providing it with updated data in recent times.
That said we noticed a bug in the framework used for it which, in combination with increased usage of the service, caused a critical error in the application. A simple 'turn it off and on again' fixed this for now so you will see the filters again. Also we will monitor this during our search for a permanent fix of the issue.