I watch the lessons on an iPad. As I progress, I often pause the playback to work on the exercise. Sometimes I go back a step to the previous video. And of course eventually I turn the iPad off until next time. I leave it open to the current exercise when I do that.
In any of these scenarios, the “Completed” checkbox can fail to automatically set itself. I noticed that when I was in Module 2 and the lessons page showed < 100% complete on Module 1. Also, if I manually check that box, there is a strange alternating rectangle on either side of the box that runs for several seconds, after which sometimes the box is turned on and sometimes not.
Returning to the current lesson the next day is also temperamental. Sometimes it works, sometimes not, and then I have to try going back to the course overview page.
Does anyone else have these problems?