Yes, the switch needs to be in FWD or REV to start the drive and to run the machine. Sounds like the low end calibration is set a little high so the drive is providing some power to the motor even if the pot is bottomed out. The drive likely has adjustments to set that. I don't usually count on the thing not spinning with the drive energized. If the spindle is not supposed to be moving right now then I want it 'off' not just turned down. It doesn't have the pot+switch like the X2 does where it's physically 'off' at the bottom of the speed adjustment.
CNC: Making incorrect parts and breaking stuff, faster and with greater precision.