Hi,
Thanks for bringing this to our attention. We're currently looking into ways RailClone can handle these situations but in the meantime, if your spline is flat on the Z Axis, you should be able to turn Off Properties > Deform > Bend for the fence panel segment. If the slope is gradual you may find turning on Stepped mode is enough to follow the spline. Our libraries suffer from the same problem, these should be fixed too in the next update.
Many thanks,
Paul