Difference between using Retained Logic and Actual Dates when scheduling progressed activities

In P3, we had two methods of calculation (scheduling), retained logic and progress override. In P6 we have retained logic, progress override and actual dates. I have always used retained logic when working in either P3 or P6 but I have been having trouble with P6 when trying to identify the true driver of an activity when using retained logic. P6 will show completed activites being the driver of an activity when they should not be and yes, I have traced the predecessors all the way back to the original project start milestone and do not have uncompleted activities or constraints that would cause this. Basically, P6 will show every completed activity as a driver with the earliest start date for each being the first working