Under certain conditions the completion state of an activity can be in a broken state, this issue only seems to affect the admin user.

Steps to reproduce:

1. Log in as admin
2. Create or edit a course
3. Add and activity and set the "Completion Condition" to "View the activity"
4. Enrol the admin with a role different from "Student"
5. View the activity
6. Edit the activity and set the "Completion Condition" to "None"
7. Edit the activity again and set the "Completion Condition" to "View the activity"
8. Go back to the course and you should be able to see the completion dropdown status as "To do" and the only task inside, "View", as done. Viewing the activity again doesn't changes the dropdown status to "Done", is stuck as "To do".

Attached a video reproducing the issue completion issue.mp4