I can see that this question has been asked before, but sorry it's not clear to me how to solve this the problem.
I have a Types custom taxonomy with about 20 terms. The taxonomy is available for two custom post types, but at this time only about 10 terms are selected for each custom post type.
I've created a parametric search for one of the post types that includes a multi-select list option for the custom taxonomy. I would like to limit the list to only terms that are not empty for this one custom post type. What is the best way to accomplish this?