Hi AndrewB!

This article details a few reasons why videos may not be showing as completed: https://support.khanacademy.org/hc/en-us/articles/115002789111-Why-aren-t-videos-showing-as-completed-in-my-profile

If the videos are still not being shown as completed after following the instructions in the article, please submit a support ticket with screenshots showing the issue. 

I hope this helps! Please let me know if you have any further questions.