Elroch

The posts here enabled me to achieve what seems to be a workaround for the problem by switching to using V2. I am not sure there is any disadvantage to this.

I am not sure there is a simple way. You can do it using the API.

You can download it. The problem is the limit of 10,000 datapoints per week is tiny when there are calls and puts for many strikes.

As of now, the web interface appears to be working!

When this happened, I thought it was deliberate deactivation of the demo account, but now I see it is probably a site bug. The buttons diverting to the live accounts would be an odd behaviour to implement deliberately, so I suppose that is a good thing! Note that trying to login to the demo account rather than using live credentials and then pressing the button for a demo account doesn't work either.