Some of the fancies themes that we installed, evolve, Customizr among others, act up weird when WPML gives /en/ for neglish and /ko/ for Korean. When going to the root folder, WordPress give zero output.
BUT in some sites that were somehow set up differently, the english is set up as / isntead of /en/ and it works.
We may need to contact WPML support for help, or just use another theme.