It depends on what you mean by “display multiple taxonomies or categories, regarding one post”.
If a post is a member of multiple categories or taxonomy terms, Breadcrumb NavXT only supports selecting the terms from one taxonomy per a post type (which you can specify in the Breadcrumb NavXT settings page).
When dealing with hierarchical taxonomies, Breadcrumb NavXT will pick the first taxonomy term that has a parent term. Thus to show a full hierarchy it is recommended to pick the lowest level term as the one that the post holds explicit membership in (as the post will have implicit membership of all parent terms).
Tools such as Order Bender can help when you have selected multiple hierarchies and really only want one to show up.
If you want Breadcrumb NavXT to display all taxonomy terms in the trail for a page, you’ll need to extend the bcn_breadcrumb_trail object to support that behavior (and use the bcn_breadcrumb_trail_object filter to pass in your extend version of bcn_breadcrumb_trail to have things work seamlessly).
