This only happens in a mono audio track.
Rotary plugin is producing a low (below 30hz or so) rumble or noise even just inserted and in stop mode…you can see it clearly in the output of the channel.
- Create a mono audio channel
- Insert rotary plugin
Sorry - can’t repro anything like that here…
Couldn’t see in your sig… what OS are you on…? 32/64 bit…? Cubase Pro/Artist/Elements…? Compare to mine and see if something there might have a bearing on why I’m not seeing your issue. Maybe.
Wow…interesting…I’ve just tried to reproduce it and screen capture, but I couldn’t ! Yesterday I could reproduce it every time…I guess its one of those things which you have to wait until the next time the conditions are just right! 
Thanks for trying anyway. If I can find more info I will post here…By the way I am no 32 bit 8.0.10 K2600 i7 with 16 gig ram (1600mhz) Win 7 64 bit…
+1 in 8.0.20
Happening on stereo tracks too.
Confirmed…
but it is Rotary’s Overdrive going into the bass rotor that is causing this.