I just finished building my 2020 i3 and I am having an issue when trying to home Z. Everything I tested up to this point has worked great. Basically when I connect using pronterface and home the Z axis the motors hum and seem to have a hard time moving. When I press the end stop while it is trying to home z, the printer moves like expected. Jogging the printer also works like expected. I am uby ForceFedDSM - Prusa i3 and variants