Replication steps:

1. Log in as admin
2. Navigate to Site admin > Development > Experimental > Experimental settings
3. Check "Enable group members" (onlyenablegroupmembersonly)
4. Navigate to Site admin > Advanced features
5. Check "Enable conditional" (accessenableavailability)
6. Navigate to a course
7. Navigate to Course admin > Users > Groups
8. Place some users in groups
9. Click the Groupings tab
10. Create some Groupings with one or more groups in each
11. Navigate to Cours admin > Edit settings
12. Set Format = 'Topics format' and Course layout = 'Show one section per page'
13. Save settings
14. Edit a section (topic) somewhere in the middle of the course
15. Under "Restrict access" set "Grouping access" to a grouping
16. Log in as student who is not in the grouping with access to the section
17. If viewing a single section, click "Return to main course page"
18. Note that the Course page shows the correct list of sections (without grouping restricted section)
19. Note that the Navigation shows the correct list of sections (without grouping restricted section)
20. Click on the section before the grouping restricted section
21. Note that you can see a link to the grouping restricted section
22. Click on the link - an error is shown

Sorry, but you do not currently have permissions to do that (View hidden sections)

More information about this error

Debug info: 

Error code: nopermissions

Stack trace:

line 704 of \lib\accesslib.php: required_capability_exception thrown

line 112 of \course\view.php: call to require_capability()