HTML5 canvas scales however the UI's actual position does not

Hi There, I seem to be able to constrain how the canvas chooses to sale the visible game window by setting

Module[‘UE4_fullscreenScaleMode’] = 2;

in MyProjectUE4.js, however when I try to click UI elements its acts as though they are still scaled based on the actual screen resolution, such as a button to close a menu is not aligned with where the image is, but where it would be if I left it at

Module[‘UE4_fullscreenScaleMode’] = 1;

Does anyone know why this is occurring?