Thanks for the help. But it’s still not redirecting with:
add_filter('acf/save_post', 'stripe_payment_redirect', 20);
I’ve tried removing the if statement and it still doesn’t redirect to payment.
I need some sort of if statement though because I have the ability for users to edit the submitted post. And I do not want the redirect to fire when they are only editing.
The strange thing is; when the if statement is removed; that when editing the submitted post, the redirect works?!