Problem Fix

// Saves the content of our meta box
add_action( 'save_post', 'save_meta_details' );

// WP meta box attributes
function save_meta_details( $post_id ) {
    global $post;
    // Skip auto save
    if ( defined( 'DOING_AUTOSAVE' ) && DOING_AUTOSAVE ) {
        return $post_id;
    }
    // Check for your post type
    if( $post->post_type == 'menu' ) {
        if( isset($_POST['price']) ) { update_post_meta( $post->ID, 'price', $_POST['price'] );}

    }
}