I just had a reply from @Elliot Condon who reminded me that the documentation pages like http://www.advancedcustomfields.com/resources/functions/acf_form/ have a drop-down at the top…
The 'new_post' array is only for V5, but V4.x uses 'post_status' => 'draft' and some other goodies.
If any of you with the problem are on V4.x then this may be helpful – it’s different sample code in the documentation 😉
