Question: AudioTools:-Preview - broken with Statistics as compared to M12

In Maple12 and 2017 we can load a .wav file and Preview no problems. 

The problem occurs when we apply a moving average from the Statistics package and then attempt to Preview the result. Warning - if you don't limit the size of the number of elements when executing the Preview you will freeze and lock up your computer as it attempts to output to the display the errors on each element.

For example.

Using the windows Ding.wav

with(AudioTools):
a:=Read("c:/test/Ding.wav"): #just a random test location I have the Ding.wav file in.
b:=ToMono(a): #changing to Mono.
c:=b^2: #squaring the signal.

with(Statistics):

d:=MovingAverage(c,30):

Preview(d[1..5]) #selecting a small number of values so I don't lock up my system.

Now Preview(d) works in M12 (ie there were no errors and a plot was presented). 

Why doesn't this work in 2017?