I’ve since found a different solution. But as this can be of utility for others, I’ll give more info. None of the above are post types. They are both taxonomies. With ACF we have the ability to add custom fields to taxonomies. And so I’ve added a taxonomy field type to a taxonomy. I’ve categorized “projects” (taxonomy) with their respective “clients” (taxonomy). I was then asking for a way to list “projects” belonging to a client on a “client” taxonomy template.
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