When I attempt to, I get the dragon spinner indefinitely. I am playing through Kongregate, and I've already purchased the Kreds to buy the pizza.
Are you in fullscreen at the time? I found an issue some year ago or so where Kong's purchase prompt doesn't show up if you're playing with the game still embedded in the rest of the page. It seems to be Kong's issue, but CH could warn about it. If this isn't your issue, then I don't know. You might e-mail support@cardhunter.com, but @mikey76500 has already brought their attention to it on the forum in the last couple days.
Well, it doesn't sound like the same issue, then. However, to be clear, what I meant was, when IN fullscreen, it sat there spinning for me and did NOT work, but when NOT in fullscreen, then it DID work fine.
@ParodyKnaveBob: It's not working for me, PERIOD--fullscreen or normalscreen--still. I can't really advance in CM because of it, so it's more of a thing than ever, now.