Ok, it’s the same one I use. I assume you have already tried connecting the wires by turning the connector 180 degrees.
Check, just in case, that the motor connector pins correspond to SIG, VCC, GND in that order. By the way, check also the state of the connector pins, to discard that it could be due to a bad contact.
Is the servo motor powered? There is 5V between the center pin of the PT1 pin set and the one closest to the edge of the board?
What Gcode are you using? These are the ones that I use to check the functionality:
M3 S900 – Open gripper
M3 S0 – Close gripper