I have had this issue before on my PC and it was caused by over aggressive blocking of ads. On Windows you have what is called a hosts file and you can use that to block all kinds of things.

It had blocked one of the bravenet URLs, I think https://www.bravenet.com/local_assets/, which seems to be the one is uses to get the captcha.

Saying that I have no idea why it would be blocked on a Mac or even where you can go to check. But turning off ad blocking might help.

In most browsers on PCs at least you can bring up debugging info (in Chrome hit F12) for a page and see any errors happening such as not being able to get to the Captcha URL.

Simon

Location: Wellington

Thank you Simon - I had the same issue whilst using my iPhone using 3G (but fine on wifi) and my father his Samsung Phone. It works perfectly on my iMac however.

I have asked if the issue can be looked into but have heard nothing back yet.