Hello Lashan, as Hans-Peter Baier already explained, the "update according to tasks" does unfortunately not aggregate staffing data - which is a shame because all data is available. Even worse, unless you enter the staffing distribution manually, you will not see the results in FES.
There is no improvement in this area with later SPs, also in PPM 6.0 the behaviour is the same.
We have meanwhile done the coding on ourselves, but it is not a simple task.
regards, Johannes