SmallBlog Using Customize Won't Save Menu changes

Hi,
I am using a child theme for the SmallBlog theme – which by the way is great! But noticed that when I use the shortcut “Customize” drop down to make changes to the theme menus (like changing a menu label and reordering) the changes won’t save, even after hitting save and publish. The only way it would save is via the regular route “Appearance > Menus”. Any ideas why that would be? Thanks!