adding ‘new_post’ => false,
doesn’t work either even tho documentation indicates it should:
/* (int|string) The post ID to load data from and save data to. Defaults to the current post ID.
Can also be set to ‘new_post’ to create a new post on submit */
‘post_id’ => false,
There once was a man from Nantucket…..
You need to write a filter so that when the post is saved the featured image is set for the post. Grab the image info from the acf field and create a filter for ‘acf/save_post’ action. The function should have something like this:
add_post_meta($post_id, ‘_thumbnail_id’, $value);