Put a point in the center of the circle
Turn on "use entry point" and "use exit point"
Select the point before the circle.
Enter the blend rad.
Enter the overlap.
Use computer comp not control comp.
Using control comp is giving away control of your tool paths. BAD
Only use cutter comp (control comp) for tight tolerance work.
Works every time.
Also pre drill the point if you can then the plunge is much nicer.
Goodluck