Interesting, perhaps it has been fixed. I need to try tomorrow. In August it was definitely broken for several weeks for multiple people.
I still recommend some cash. In many cases cashiers have hard time using foreign cards since there might be prompts they are not familiar with. It's sometimes slow and awkward to pay with foreign cards. But if you prefer it and stay around Tokyo you are 95% fine with a charged IC-card and a credit card.
Actually I have even noticed some places and events in Tokyo do not even accept cash.