One workaround I've come up with is to use an Offset effect on the stroke layer of the rectangle.
- Set the stroke to be the same color as the fill
- Leave the Offset distance to 0 pt
- Chang the Offset method to "Round"
- Experiment with the Stroke width to get the corners you desire
This isn't perfect, and you have to play with the size of the original rectangle as well, but it should give you something until ESRI fixes/implements the functionality.
Dan Patterson, it seems like that dropdown only changes what the example swatch looks like, rather than effecting the actual polygon (as evidenced by the wildly irregular polygons included in the dropdown). Is this correct?