Hi Ross, I have a search form configured to search a custom post type ‘Recipe’ with a couple custom taxonomies and 2 post_meta fields set in the UI.

The post_meta fields ‘related_products’ and ‘related_friend’ contain a post_ID of their respective post, Product and Friend. The search will return results for the related_products meta field but not for the related_friend meta field. I have included the post meta from the database on the same post ID. The search form is on the Recipe post page http://sweeteners.wpengine.com/recipe/stevia-buttercream-frosting/

From the database = no search results
meta_id 8737
post_id 493
meta_key related_friend
meta_value a:1:{i:0;s:3:”492″;}

From the database = search results
meta_id 4744
post_id 493
meta_key related_products
meta_value a:1:{i:0;s:3:”495″;}

Post 493 is a recipe post type – http://sweeteners.wpengine.com/recipe/stevia-buttercream-frosting/
post 492 is the related_friend – http://sweeteners.wpengine.com/friend/katherine-clapner/
post 495 is the related_products – http://sweeteners.wpengine.com/product/organic-stevia/

You can see the post relationships for related_friend and related_product on the recipe post as well.

Any insight why the related_friend post meta does not return any results would be greatly appreciated.