Alright, sorry for the multiple posts @fabian. Here are some repro steps for the bug on Sonar Platinum.
1.Compile Noisegate from the JUCE 4.2.2 tip. (I used Visual Studio 2013 with v120 Platform toolset while testing this)
Load Sonar Platinum and place Noise Gate (vst2) on first audio channel with no audio on the channel.
Create a second audio channel, load a sample and send it to the sidechain input of Noise Gate on channel one.
Drop the threshold of the Noise Gate plugin to 0 and notice that the sidechain input signal begins to play out of the right channel on the main bus of the Noise Gate plugin.
Strange thing is that this is what is happening on the vst3 version of my app, however it isn’t occuring with the vst3 version of Noise Gate.
I know that in the multi bus guide you say to avoid using the sidechain on vst2, but I think this bug may be affecting my vst3 plugin. Still trying to dial in exactly what is going on, but thought this may be useful for you guys : ) let me know if you find anything!