you were right!
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patch PR-C:001 Harmon Mute uses this
Select the patch, press LFO&Ctl (F5) then press Control (F3)
Number 3 is set to pitch bend -> CUT: +20
So cutoff will increase by 20 if you pitch up and decrease by 20 if you pitch down.
It's a bit confusing because there is another "Control" menu under "Common" (F1).