Kharis Sulistiyono

Dropdown hierarchical category in WordPress post write panel or editing screen. It makes the categories or taxonomies list in a better UI which enables show/hide toggle of child categories. It comes with plugin settings page where you can select in what custom post type(s) the dropdown UI will be applied to.
The idea comes from default WordPress hierarchial post categories which looks not good. Imagine that there are a lot of child categories. After selecting child category then publishing or updating a post, the arrangement seems not pretty — the child categories moved away from its parent. This plugin tackles that situation.

WP Dropdown Hierarchical Category UI

It makes the categories or taxonomies list in a better UI which enables show/hide toggle of child categories. Supports any custom post types.

Amin Nazemi

This plugin disables Pagination in navigation menu lists and preserves taxonomy hierarchy. 
Also, it helps you when you using WooCommerce and you have more than 50 category items. 
It can preserve WooCommerce category hierarchy.
FEATURES
<ul>
<li>Disable Pagination in nav menu add item lists </li>
<li>Preserve hierarchy in category nav menu add item list and posts category selector</li>
<li>Automatically scroll to first checked item in post category selector </li>
<li>Preserve WooCommerce category hierarchy</li>
</ul>

Preserve Taxonomy Hierarchy

Preserve hierarchy in posts category and navigation menu editor lists.

WP Dropdown Hierarchical Category UI vs Preserve Taxonomy Hierarchy