In the RDC6442G controller, the multi-point positioning function cannot be used when the U-axis rotates

My controller is RDC6442G. I set the U-axis as the rotation axis and found that the multi-point positioning function cannot be enabled. No matter how I adjust the software parameters, the system still cannot provide multi-point positioning function. Is there any limitation to this? Is there a problem with the U-axis? Any suggestions? Thank you!