When opened in the Gantt tool all tasks are not displaying. When you look at the task list in Clarity you see one number, but in the Gantt, you see less when you expand the hierarchy.
There is a problem when using Firefox, the scrollbar for the Gantt list doesn't work correctly
Release : 15.7.1, 15.8, 15.8.1
Component : CLARITY PROJECT MANAGEMENT
The problem is related to this known defect: Gantt Vertical Scrollbar Disappears in Firefox - DE54302 is fixed on 15.9 and back-ported to 15.8.1 patch 2.
Workaround: Use Chrome or Edge