I have almost finished Crash Course, but the links are not working, they keep you leading to the same section. I am in chapter 12, it stucks in the same point regardless the link you or button you click.
yes, i experienced the same problem. i think the mendix backend server was crashed.
as a workaround, you may go back to the learning path, and click continue path to enter the next chapter.
however, i gave it up today. i'll come back and have another try tomorrow.