When I test it on https://try.discourse.org/ it’s working correctly. For staff users, it should be displaying a icon next to the username of users with staff notes. The icon is only displayed on topic pages.
If you have a user who you know has a staff note attached to them, do you see a count of staff-notes for the user when you go to their summary page? Do you see any errors in your browser console on either the user page, or the topic page for users who should have staff-notes? Can you try creating a new staff note and see if there are any errors in your browser console?