Issue with upgrading to Pro

Hi everybody,

Was wondering if someone could help me out. I almost literally bent over backwards today trying to upgrade my Zoom account from Basic to Pro. My previous Pro subscription expired a day ago (forgot to renew it in time) and today I wanted to upgrade back to it, but whatever I do I get stuck with the greyed out "Upgrade to Pro" button. 

I have billing and payment info all set up as they should be, but the button just won't become active. The chatbot is spectacularly unhelpful and last time I contacted support half a year ago on another issue they replied a week later, which was spectacularly unhelpful as well.

I'd be very much thankful if anybody could advise me on the issue. Thanks!