Apart from my button not disappearing, I basically have the same issue as this post: https://www.itthinx.com/topic/subscription-page-not-redirecting-to-paypal-website/
However that post is closed for replies and does not contain the answer. Looking through some of these support topics they seem to end in email solutions. May I suggest a contact form or to please include the solution in the thread?
If you wish to test it you would have to sign up at http://esbb.org/member-registration and then try to purchase a subscription, you should have difficulty redirecting to PayPal. Although sometimes it simply works. Could it be PayPal’s dev area?