When cutting a square corner the toolpath will be an arc equal to the radius of the tool. This results in a sharp corner on the part. As for the arc being short line segments instead of a circular interpolated move, under machining preferences output arcs (and spiral motions and helix motions) as linear segments should be disabled (unchecked) unless there is some reson your control requires any of those options. To force the MOP to generate G2/G3 moves over line segments, cut arc fitting needs to be enabled in the plane the arcs are generated in (on a VMC this is usually XY) with a tolerance less than the overall tolerance. I set the tolerance (on the cut parameters tab) to .0001" and the cut arc fitting tolerance (on the advanced tab) to .001".
That is what has worked for me.