Same here - CC 2018 and Sierra 10.12.6. Nothing at all happens when I click on any of the arrows/triangles
1. nothing happens when clicked
2. all documents
3. yes CC 2018 (13.0.1)
4. Mac OS 10.13.1
We would be needing a little more information such as...
1. What happens when you click on the "arrows" before each entry of the pre-flight panel
2. Is this issue specific to one document or is reproducible with all documents you create?
3. Are you using the latest version of InDesign ( CC 2017.1)?
4. Your MAC OS version?