In PLAY PATH dialog box, View > Collision Checking and Stop at Collision, use the defailt Diplay Speed or fast display speed, the collision may not be found. Use the slow display speed, the collision can be found.
In help topic "Collision Checking Options", there is a note: The lesser the speed of tool path display, the higher is the accuracy of collision checking.
Now the question is: How to set the display speed value so as to the collision can be found and cannot leave out any collision? Video Link : 4392