I have just had a look. The reason why you cannot download your data is because your experiment’s status is INACTIVE. We moved older experiments without recent sessions to INACTIVE when we migrated to our new server.
Unfortunately, the [Download results] button is still clickable, which is my mistake.
I have just changed mbl.georgetown to PILOTING and could download the data without problems on my end.
So all you need to do is change the status of your experiments to PILOTING, and download the data.
On my end, I will address the issue by desactivating the [Download results] button when the experiment is INACTIVE and warning designers about what they need to do.
Thank you very much for bringing this to my attention! And sorry for the trouble.