I am using JUCE v6.0.8 and Ableton Live 11. When I add my plugin to a track I see that the number of input channels is read as 9, even though the track is stereo. This only happens in AU format in Ableton Live, all the other formats and DAWs show up the correct number, 2. I tried it with an empty project and added some debug messages:
getTotalNumInputChannels() = 9
layouts.getMainInputChannels() = 9
This doesn’t happen with JUCE v6.0.4.