OK, I think I have this, and it’s not a bug.
Fn your form arguments include
'post_id' => 'new_post',
Then ACF creates the new post automatically using the content of
'new_post' => array(
'post_type' => 'startups',
'post_status' => 'draft',
),
If you want to create a new post of the type startups and you want to handle the details of this yourself in an acf/pre_save_post filter then in your form arguments use
'post_id' => 'new_startups',
and in the pre save post filter use this the test
if( $post_id != 'new'_startups )
I hope this explains things. It seems I was under the same impression you were from reading the documentation.
