You have a course with "Activity names auto-linking" filter activated. There you have an activity and a section with the same exact name. If you are on an activity and you try to access the section using the navigation (instead of the course index), you arrive to the activity instead to the section.

For example: A section called 'Quiz' and a quiz called 'Quiz'. If you are in an activity inside the 'Quiz' section, and you click on the name of the section ('Section') with the intention to return to the section, you actually enter the quiz 'Quiz'.

Workaround: Use the course index