Can't Edit Custom Menus

I am using a theme (Touchfolio: https://dimsemenov.com/themes/touchfolio/) that supports 2 custom menus. I can create the menus and they work as expected, but once made I can’t edit them. The don’t show up as tabs under Appearance/Menu and if I try to create a menu with the same name as an existing me menu, I get the following message: “The menu name Menu1 conflicts with another menu name. Please try another.” Any help would be much appreciated.