I answered this correctly, but it was marked as wrong. The only thing that has changed is that I have just switched to Brave for my browser (though I am not convinced that was the cause). No other words had this problem (so far). I opened inspect console and there was one error about newrelic being blocked, which I would have expected given the nature of the browser.
I see this is a problem people used to have 5 years ago. Hopefully just a browser compatibility issue and not a regression.