I’ve noticed that VST3 plug-ins (including the JuceDemoPlugin on the develop branch…) have an issue with automation. If you draw a simple straight ramp in a parameter’s automation lane, the parameter values wobble intermittently, which is easily noticeable with a GUI open and a big enough rotary.
I’ve reproduced this with 3.6.5 and 3.6.7 of the VST3 SDK.
I have managed to catch the call which is causing it, and it is coming from EditController::setParamNormalized in the VST3 SDK, which is occasionally being called by the host with a value slightly lower than is being set in JuceVST3Component::processParameterChanges in the wrapper.
This affects both Windows and Mac, Cubase v9 and 8.5.
I’m not entirely sure why this would be happening, perhaps someone here will have more of an idea!