I have submitted all my answers, why does my course page show that I have incomplete exercises?
To pass some of the exercises a peer review is required. The system does not consider these answers " completed " until all review process requirements are met. Even though your answer is fully submitted and done, the system is not yet done with the "completing" process. Usually, within a few days, the system will catch up and the score on your course page will be updated.
You can read more about the peer-reviewing process here.