Rekordbox 6.6.5 - Analysed track waveform quiet then loud on waveform - Analysis problem?

I have had this problem with the latest version (6.6.5) and the previous version (6.6.4).  Certain tracks don't analyse correctly and the waveform appears thin (quiet) then thick (loud) at random spots.

I have deleted the track and re-downloaded it, then re-analysed the track and the same problem happens.  

I have turned off auto gain

I have experimented with turning on & off the cloud analysis, then re-analysing the track and loading it again onto the deck and the same problem occurs.

I download my music through itunes.

Is there a bug or is there something I can toggle in the preferences to stop this happening, so that it analyses the track correctly and creates the correct waveform?  Does anyone have a solution?

Thanks