I have had several experiences of completing a lesson successfull both by exam and by doing the lesson and the success has not been posted. This is a huge disincentive to participate
So does it tell you that you are on the next level (and then it disappears) or does it time out earlier? If it is on the site, it is not a sync issue usually but I had had cases where my connection dies just when a lesson is done - so the site never knows that you had finished the lesson...
I complete the lesson but the system does not advance/I take the quiz for the next level but the system does not reflect the change-it is like I am being ignored after completing the process.