Taxonomies not showing in UI

I’m trying to add categories and tags to a custom post type, so added this line:-

'taxonomies' => array('post_tag', 'category'),

however they are not showing up in the UI am I missing anything, the full register post types code is below.

register_post_type( 'pg_offers',
		array(
			'show_ui' => true,
			'labels' => array(
				'name' => __( 'Offers' ),
				'singular_name' => __( 'Offer' ),
				'add_new' => __( 'Add New Offer' ),
				'add_new_item' => __( 'Add New Offer' ),
				'new_item' => __( 'New Offer' ),
				'edit' => __( 'Edit Offers' ),
				'edit_item' => __( 'Edit Offer' ),
				'view' => __( 'View Offer' ),
				'view_item' => __( 'View Offer' ),
				'search_items' => __( 'Search Offer' ),
				'not_found' => __( 'No Offers found' ),
				'not_found_in_trash' => __( 'No Offers found in Trash' ),
				'parent' => __( 'Parent Offer' )
			),
			'exclude_from_search' => false,
			'taxonomies' => array('post_tag', 'category'),
			'public' => true,
			'has_archive' => false,
 			'show_ui' => true,
			'capability_type' => 'post',
 			'hierarchical' => false,
			'rewrite' => array('slug' => 'offer'),
			'supports' => array(
				'title',
				'editor',
				'excerpt',
				'thumbnail',
				'custom-fields'
			)
		)
	);