I've had the same issue in the past, Mendix was looking into it then. It might be worth sending a ticket to support so they can look into it and add your credits.
Hi, Loai Abu Khil
Please You will ask a one question on forum and answer was right then you give the accepted that answer, you completed the Challenges or you may be accepted my answer this Question then you also completed the challenges
i hope it will help you,
Thank You !