No Anti-aliasing on overlay shapes

I’ve created a simple Circle overlay over a background image, attached.
Notice how it has a jagged edge / no Anti-aliasing.

Is this a limitation of overlays in general or is there problem? Any way to get it smooth?

In case it helps others, I found a solution.
You set the Color 1, Color Stop to be 0.1 less than Color 2, Color Stop.

E.G.
Color 1, Color Stop 49.9%.
Color 2, Color Stop 50%

It will then have a smooth edge, no jaggies.

overlay-jagged-edge-fixed