there is not too many options really. either your multimeter is not configured correctly (maybe ACV range) or it is not working correctly or the probe leads is broken or you are measuring across wrong pins or or your probes do not reach pins or there is really no voltage at X41, which would indicate hardware issue (blown fuse? check inside controller...)
Is there a fuse for X41/X4 in the robot controller? There is a fuse in the base panel of the robot for the internal I/O, this is not blown. I am not aware of a fuse for it in the controller.
I tried two multimeters as well, in DC voltage. I can confirm the 0V pin has continuity to ground with power off. I measured each pin to ground and none had 24v