Posts shows in vertical column with no grid layout

I like the masonry layout, but for some reason on my site all posts align in a vertical column on the left instead of tiling and filling the page

This theme uses Masonry script that is inside the WordPress core so you must use WordPress 3.5+ in order for this theme to work properly.
You can always add this script manually but it’s better and easier to update your WordPress installation since you can do it via WordPress dashboard without losing any data or settings.