Solidworks results for motor torque of a power screw raising and lowering a load are the same. Analytical calculations according to SHIGLEY, the torque should be different. The website Power Screws shows how to calculate the torques. I made a simple model in Solidworks to prove that probably there is a bug in solidworks. Please find attached the file. In Motion Study 4, you can see the results of the motor torque for raising the load. If you reverse direction of the force, the results are the same for motor torque.