Within the Role Visibility section is a display of all objects for the current model type.
By selecting a role and clicking on the object inside this panel, you can turn on/off the visibility of the selected object type for the selected role.
When the object is grayed out, it is turned off for the selected role and not visible on the Canvas.
Any object that has the role visibility for your role turned off is invisible when you click on the Toggle role level visibility button in the toolbar.