The part below has been processed with a 45 degree bevel around its outer curve, and was processed with Apply Rotary Smoothing unchecked. The curve however is composed of line segments, and as a result the tangent following causes Primecut to generate a piecewise motion of the azimuth axis, constant along each segment, then a small adjustment between segments, which will likely cause the machine to pause. This will not cut well.
Before Rotary Smoothing
We can see the each segment has Bevel Rotation Auto, and that the Bevel Rotation begins and Bevel Rotation Ends are identical. They will vary segment to segment however as the tangent angle of each segment steps around.
If we select one or more segments, RIGHT CLICK, we can choose Smooth Bevel Rotation Axis. This will blend each segments' Bevel Rotation Ends with the following segment's Bevel Rotation Begins, setting both to their average:
After Rotary Smoothing