The behavior you describe I’ve only seen one way. If I home the machine, release the steppers, move the machine manually, and then attempt to move electronically, it will not move to negative values. Though the router is at a new location since I moved it manually, the firmware still thinks I’m at the minimum position of my machine. You can get around this problem by executing a G92 X0 Y0 Z0 before attempting any negative moves. So I’m guessing somewhere in either your process or in your wiring your machine thinks it has been homed.
Ok thanks I think I will have to manually home every time.