I have the same issue. It is erroring on adding to basket. I have tried over a couple of days, browsers and even different accounts (as I was trying to buy one for my wife too). I have also tried the purchase journey in German and this hasn’t helped.
It is erroring when trying to add the pass to the basket so won’t be anything, in this case, to do with the Visa 3d as it is before that in the sales process.
I am pretty sure this is an issue on the website, but cannot see anywhere you can raise a query via chat or email. You have to call which I don’t really want to do from abroad and in German.
Edit - Trainline is not an option as it simply redirects to sbb.ch