My problem. 

Im trying to create a simple rectangle with round edges.

Method
Create a new layer with transparent bg.

Create a simple/complex shape.

Gausian blur 20 IIR

Adjust the levels of the layer to roughly 84 , 1 , 152 ( Still retains a slight feather :) )

Using the above on a solid bg works perfect but when you try to create it with a transparent bg the levels have no effect on the layer.