We found the following problem in V7.1.5: if the wav file is stored in the lightshow folder, the waveform is not displayed (this is fixed for next version).
But, outside of this problem, we always see the waveform.
If your wav file is not in the lightshow folder, and you do not see the waveform, please send us the file (if too big, please use
http://www.wesend.com or similar).