Hi @Exelmans Graphics
Thanks for the info.
because your field is a multi-select, the data will be saved into the DB as a serialized array of user ID’s.
The WP_Query does not contain any feature to search for serialized data, this is why we need to use a LIKE hack.
This is all documented on the reverse relationship documentation here:
http://www.advancedcustomfields.com/resources/field-types/relationship/
Note: The relationship field saves it’s data as a serialized array of post_ids. It is exactly the same as what you have, so the technique will work the same too
Thanks
E
