This is a situation that I ran across recently after using WPMS as a staging environment.
add_theme_support( 'post-thumbnails' );
set_post_thumbnail_size( 610, 230, true );
add_image_size('homepage-thumb', 150, 300, true); // custom size for the homepage
Typical scenario, right? I've enabled post-thumbnails, set the default Featured Image size and then I've created a specific size for the homepage.
Guess what? In WPMS, add_image_size does not work. The crop feature is completely ignored and you're only choice is a proportional sizing.
This what a MASSIVE irritation to discover. Please fix this.