I tried to repeat tutorial and reset that from profile settings. Marked the cube, but could not move to the next step - pressing Check my work didn’t do anything. I pressed F11 in Chrome 70 and saw errors.
Let’s Encrypt certificate for https://data.eyewire.org/volume/15656/segment/enumerate_metadata expired 2 days ago. Perhaps this why main site can not fetch this resource and fails, making me unable to move to the next step.