Long time ACF (PRO) user here. First off, many thanks for a fantastic product. ACF have made it so much easier working with WP. 😀
I’ve run into a problem with search in the post object field not returning any results for media/attachments. I can find and select media / attachments in the listing, but get “no results” when using search. See images below.
I can search for pages and posts just fine. But get no result when searching for media / attachments. The client have many posts and attachments (pdfs) so scrolling through the whole list to find a document gets quite cumbersome.
Does search in post object / relationship field only return post types “page” and “post”? If so, how can I add “attachment” as a searchable post type?
I’ve just tested it on my installation but failed to reproduce this issue. Maybe there’s something on your site that modify the search query. Could you please try to reproduce the issue on one of the WordPress’ stock themes (like Twenty Sixteen) with only ACF activated? If it disappears, then you can activate the theme and plugins one by one to see which one causes the issue.