Cog meaning the Display Options button in the schedule editor (the same UI 'row' where the date navigation is)?
Assuming those users have the 'Historical Adherence > View' permission, the schedule is published, and the period being looked at is in the past, then my only thought is a Division issue. E.g., agents in a division where the user doesn't have access
https://help.mypurecloud.com/articles/view-adherence-information-in-the-schedule-editor/
If nothing obvious, then I would recommend opening a support ticket. I was able to see adherence information in a production environment demo organization (where I only have read-only access to schedules).
------------------------------
Jay Langsford
VP, R&D
------------------------------