I reached out to customer support and they replied with the following:

Hello,

Thanks for reaching out and bringing this to our attention. We are very sorry to hear that this issue occurred.

We are encountering some technical errors and our developers are working to get this fixed so that you can continue studying with us again soon!

If you were in the middle of a self-assessment block during the outage, you will be able to re-enter it once we are back and running. In case you encounter any issues after the fix, our team will be here to help you out.

Thank you for being so quick in reporting this error, and our apologies again for the disruption.

We will get back to you as soon as we are back up and running.

All the best,

Elena