Hate to be bring bad news back at you….but the customizer works for me and I can open the tabs with it. I did my theme updates on WP 3.9.1, updated the live demo sites, and still they work. I did this with Encounters and Celestial Reloaded. I can only suggest you grant me admin access (send through Email Support) and I will check this out but I can honestly guarantee you that the latest versions are working in WP 3.9.1.
How did you update the theme(s) ?
Here is a screenshot of the first tab opened…running on WP 3.9.1 and the latest version of Encounters which I installed just moments ago on a live test site as well.