If you look at the general properties of the portlet it does say
projmgr.npioRoleCapacity and System data provider
Investment Role Capacity
or for projects projmgr.invRoleCapacity and System Provider
Investment Role Capacity
but there is not such portlets.
There is a portlet ID = 5003002
projmgr.roleCapacity System Provider
Roles with Resource Aggregation which looks more like the Role capacity view than the Investment View: Role Investments - Capacity
Have not tried if changing the portlet copnfiguration will change the portlet.
There are system portles which are not available for user configuration.
On the other hand the Investment object instances are not accessibple directly through the navigation menu, but throgh filtered by the investment type and maybe therefore the changes in the investment object view are not directly viewed in the GUI either.
(You did publish, didn't you and logged out and in again?)
Martti K.