Answer 1

Yes, I have lost everything too from that exact same course

Answer 2

Might be that you have deleted or removed the course from your "my courses" list.
Go to learn section, then go to courses and then add the course to your "my courses" list.

Hope this helps

Answer 3

Oh good, it’s not just me. Any way to recover?

Answer 4

Same here, lost all progress :(