How to pass “I’m not a robot”

I didn’t have trouble answering questions in the past, but now I fail the human verification check.

Basically, instead of a CAPTCHA, I can check “I’m not a robot”. When I check it, it goes away and I get a spinning circle animation.

I don’t seem to be able to do anything afterwards; I waited a few minutes, nothing further happened.

I tried with Firefox and Chrome, with and without my ISP’s proxy, but it’s all the same.

So, how does one pass the human verification stage? I am pretty sure I am not a robot, but am unable to convince Stack Exchange of that.