I have experienced that sometimes the themes update and then do not support custom menus, unless in widgets.
Not certain why they would do this, yet I have seen it happen.
Have you checked "theme Options"
Also when you look at the "Menus" in "Appearances"
they are in alphabetical order if you have more then one menu.
Try to name the menu that you want with a name that is at the top of the list.
This sometimes then pulls the first menu to your menu bar.
let me know if this helps.