The post ID in acf_form() needs to match the post ID your checking for in your filter
acf_form(array(
'post_id' => 'new',
'new_post' => array(
'post_type' => 'app'
),
'submit_value' => 'Create'
));
You can use it for multiple post types by varying this ID for example new_page, new_product, new_whatever_you_want.
If you use new_post in when you call acf_form() ACF will automatically create a new “Post” post and your filter will do nothing.
