CinemachineSmoothPath and DollyCart: Orientation snaps when looping past last point

I am using a CinemachineDollyCart on a looped CinemachineSmoothPath. When the path position passes the last point an loops around to the start there is a very visible snap. I've isolated the problem to the orientation. The position loops smoothly. To reproduce, make an oval or circular looped smooth path with four points. When the speed is set low enough, there is a very visible hitch in the orientation as the cart passes between point 3 and point 0. Can anyone offer a solution?

 

@gaborkb, Thank you, but that did not help.

 

The World Up override is a Transform, not a Vector3, but I do not believe it is related. Perhaps I have not communicated the situation clearly enough. I have a circular CinemachineSmoothPath, with four Waypoints. I have a CinemachineDollyCart which has its Path field set to the CinemachineSmoothPath. A default CinemachineVirtualCamera is childed to the cart. The cart automatically moves along the track when the speed is non zero. The camera's fixed local rotation is 90 degrees in y axis and a few degrees down along x so it is looking toward and below the center of the track. As the cart is moving, the scene is smoothly rendered until the cart reaches the point on the track where it closes the loop (at waypoint 0). At this point the position of the cart updates smoothly, but the calculated orientation slightly snaps for one frame. This is easy to miss when using higher speeds. It is as if the tangent calculated for position 3.999 does not mirror the tangent calculated for position 0.001.

 

Thank you for the quick reply. I'll give the CinemachinePath a try.