I just got challenged (over on English Language) by the new "Mark all images with street signs" CAPTCHA.
I must have tried a dozen times to solve it by checking all images that had street signs, but I never succeeded.
Of note is a text input field without instructions of what to enter there. I suspect that is the problem: It is expecting input, but doesn't tell me what to input.
It's either broken or I am missing something.
I am using Chrome on an iPhone in "full site" mode.