Hi there Max,
Yes, controlling knobs and faders in Ableton with the plugin is actually a bit more complicated than doing it over an IAC bus from the standalone app.
Using the plugin, you either have to route the MIDI out and back in via a virtual bus, or use a Max for Live device from the building tools pack . The virtual bus method is complicated by the fact that Ableton strips MIDI channel information coming out of plugins: so all of the MIDI information coming from the Sensory Percussion will be condensed to one channel.
The Max Api CtrlMIDIcc.amxd is the device from the building tools Max for Live pack makes it possible to send CCs from the Sensory Percussion plugin to Ableton’s UI.
@Mason has made awesome tutorials for both of those techniques: