@meandhim, thanks for your help, still not cracked it. I don’t know how to ‘look in authors_people’.. Do you mean look at the mySQL database? This is a bit over my head.
I have moved my issue to a new forum thread, please come over there to chip in if you have any thoughts on this and to continue this. Thanks again.
https://support.advancedcustomfields.com/forums/topic/wp_query-with-meta_query-on-a-subfield-within-a-group-field/
