ah. You are comparing Sheetcam menu Mode-Simulation to Mach3 controller/CNC table results, got it. Sheetcam simulation does not use the post processor assigned for gcode production in your settings, rather it uses a simple toolpath as represented in the drawing. Thus differences in the simulation vs. actual table motion is common, depending on the customization of the post processor you are using.
I suspect this also means on the “PC” you were using sheetcam simulation also.
Thus actual cutting on the CNC table w Mach3 has always produced the result of cutting back to the programmed finish point of X0Y0.
There may be a couple of features in sheetcam that may be mistakenly in use or there could be an error or incompatibility in the post processor. Either way, the easiest way to help you troubleshoot this is to send us a customer support file.