We go to Modern UX - Tasks - To Dos, and filter. Seems that in the results the To Do Owners Max out at 9
Release : 15.8.1, 15.9, 15.9.1
Component : CA PPM PROJECT MANAGEMENT
This is working by design. Only 9 resources are shown at a time as To Dos Owners and then to see more you have to move your mouse over those resources and scroll in order to be able to display the rest of the list.