using Motion controller to record each step of movement of 6 axis robot arm. over all around 30 step recorded. During  "Calculate Animation" or "Play" mode. can notice that some of the steps the graphic/ robot arm are not moving  at all. but we  can see the "Mate Position " value changing.  

please refer to attach video. after 29 second play... all movement are stop  until last few seconds. 

Hope someone