Hello from Colorado USA,
Not sure why you are having a problem with Rreference 4 and Studio One - I have both S1 ver 3.5 (32 bit) and S1 ver 4.1 (64 bit) and Sonarworks Reference 4 works fine with both. I simply inserty it in the Main bus, choose a Calibration Profile, and switch on the SR Enable. One issue I had with Sonarworks when I first installed it was that it installed the plug-in in a folder without asking where I wanted it, and it was in the wrong folder. I just moved it to my normal VST folder, and it works fine.
Hope you get it working OK.