Impossible to control fx inside of loop?

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1

As defined as follows, the control doesn’t control anything

with_fx :lpf, cutoff: 60 do |x|
  use_random_seed Time.now.to_i
  live_loop :run, sync: :met do
    #stop
    use_synth :beep
    play scale(:E5, :ionian).choose, amp: 0.6
    sleep [0.25,0.5, 0.75, 1].choose
    ##| sleep [0.125, 0.25, 0.375, 0.5, 0.625, 0.75, 0.875, 1].choose
    ##| sleep range(0.1, 1.1, step: 0.1).choose
    control x, cutoff: 10
  end
end
2

Yes, this is unfortunately a rough edge to Sonic Pi’s FX semantics. I tried fixing this last autumn but whilst I got really far, I ended up getting tangled in knots of concurrency and had to revert.