Final Cut Ducking Issue

OK, so this is really a "thing". Ducking music, and other sounds, to make room for narration is Crucial to many different types of video project. I'm literally shaking my head in disbelief that this can't be done. I can only imagine that, in its core code, audio clips in FCPX are so segregated that they can not be made to interact with one another.

Having done substantial audio engineering, I had an "ah ha!" moment driving home, that I could simply duck the old fashioned way... by sidechaining a compressor, thrown on the track I wanted ducked. Nope. The sidechain button is still there - an obvious carry-over from its Logic Pro roots - but it does nothing... There is no option for choosing a sidechain input source. So sad, as this would be far more customizable than the iMovie, or Auto Duck, solution.

Round-tripping to an audio program - a workaround I could do with SoundTrack Pro, and on Windows with PowerDirecter (eeckk), isn't an option either.

And this has been accepted since the dawn of FCPX? Really?

I came back to Mac primarily for FCPX and Logic, and this is a Cut (omission) that isn't Logical, and certainly shouldn't be Final. Let me sidechain, won't you?

P.S. - OK, I figure its a "trackless" issue... But it should be possible to sidechain to a specific Role without too much coding pain.