By default, a custom taxonomy panel is not added to the Gutenberg editor. That means by default authors are not able to select terms in the editor. Tonya shows you how to turn on the feature.
How to Enable the Gutenberg Editor for a Custom Post Type
By default, a WordPress custom post type does not use the Gutenberg editor. Why? In this quick tip, Tonya walks you through the why and shows you how to enable the Gutenberg editor for your custom post types. Don’t worry. It’s literally one configuration parameter.