[Plugin: Custom Taxonomy Columns] Columns do not appear

I’ve installed the plugin on my site (3.3b3), and it has no effect on my post list in the admin. No custom taxonomy columns appear. This is on post type of ‘post’, which has several fully functioning and public taxonomies attached to it.

Custom taxonomies are absent from Screen options as well, so it’s not that they’re hidden.

Any idea what the problem is?

I don’t think this would be the problem, but here’s an example of my standard taxonomy registration code. Like I said, the taxonomies work fine.

$labels = array(
	'name' => _x( 'Features', 'taxonomy general name' ),
	'singular_name' => _x( 'Feature', 'taxonomy singular name' ),
	'search_items' => __( 'Search Features' ),
	'popular_items' => __( 'Popular Features' ),
	'all_items' => __( 'All Features' ),
	'edit_items' => __( 'Edit Features' ),
	'update_item' => __( 'Update Features' ),
	'add_new_item' => __( 'Add New Feature' ),
	'new_item_name' => __( 'New Feature' ),
	'separate_items_with_commas' => __( 'Separate features with commas' ),
	'add_or_remove_items' => __( 'Add or remove features' ),
	'choose_from_most_used' => __( 'Choose from the most used features' ),
	'menu_name' => __( 'Features' ),
);
$args = array(
	'labels' => $labels,
	'public' => true,
	'show_in_nav_menus' => true,
	'show_ui' => true,
	'show_tagcloud' => true,
	'hierarchical' => true, // this makes it hierarchical in the UI
	'rewrite' => array( 'hierarchical' => true ), // this makes hierarchical URLs
	'query_var' => true,
);
register_taxonomy('feature', $allposttypes, $args);

https://www.ads-software.com/extend/plugins/custom-taxonomy-columns/