[Edited for additional information]
I can't get the "Mark Lesson Completed" checkboxes to work properly. I can check the boxes, but when I go back to the webpage, the box is unchecked -- there is no persistence. This happens both when checking boxes from the individual lesson pages and from the overall season summary page.
In the past, when the box was checked, it would display the date the lesson was completed. Now when I click on the "Mark Lesson Completed" checkbox, it displays a checkmark, but no completion date appears next to the checkbox.
[Note] I originally thought this was just on the "Survival Phrases" lessons, but it seems to be widespread. Lesson tracks such as Absolute Beginner Season 3 and 4 which were working properly for me before are not working any longer. If I click on additional lessons in those tracks, they revert back to unchecked if I leave the page and return.
Hopefully it's just something simple like a server being down, which will correct itself. This problem appeared very recently, I have several lessons marked as completed for October 21st. So whatever is causing the problem likely occurred sometime on October 21st UTC/GMT. I estimate I had lessons properly marked as completed at around 10am UTC and was unable to get them to check when I completed lessons probably about 3-4 hours later.