I was just given the challenge as an RE, but when I clicked on the link, I was given the message:

I know this was a problem back in January, but it seemed resolved at the time. old report. Not sure if anyone else is having this issue or not.

Just double-checking you're sure the RE wasn't lying around for a while (ie expired)?

I have just tested this and it had worked fine for me

It was on a tab I had just opened, as I mentioned in the first post (I got the RE when the tab opened, clicked the link, and was a told I hadn't been challenged).

I have no idea if it is functioning now or not because 99% of the time this site is lagging so hard pages aren't opening at all and its using more memory than high usage games that I play (entirely separate issue that has its own topic though). Its been 2 weeks since I made the topic and I haven't had a chance to test whether its fixed for me or not lately.