Upfront Editor failed - will not open from dashboard

At around the time Upfront upgraded to v 1.2.1 (from v 1.2) my site lost all customization and the Upfront editor ceased to function. It appears that all Upfront elements are missing along with the editor itself but my dashboard still reports Upfront as active.
When the Upfront link is clicked, the home page just opens in a standard view without any editing options.