How can we reproduce this issue?

1) https://www.bookmarketing.pro/publish-package.html 2) For the promo code enter anything and try to click the button. Nothing happens.

If you put a <button> inside an <a href> link, clicking the button may activate the link and cancel the action of the button (because page navigation tends to cancel script actions). To avoid that, you usually include something like this in your <a href> tag:

onclick="return false;"

I haven't installed the new update yet, but I would be surprised if that stopped working.