Newer versions of repetier host have something wrong with the arcs (G2/G3 commands). It is a display bug. I’m not sure if anyone has reported it to repetier, but it still works when the commands go to Marlin.
My guess is they are drawing the wrong part of the circle. They are going clockwise instead of counterclockwise to get from start to the end point.
As a workaround, you can install an older version of RH, or use another program (like cncjs, or pronterface).