High pass filter, Resonance full, cutoff to 11 ( voice 6 is sounding terrible )

[Dorwarth]

Anyone had this issue ? Running the latest firmware, 1.7.5
If I turn the hp resonance and cutoff to full / max, then turning the cutoff down to approx 11 o clock , striking, toggle a key at the same time and only voice 6 is making this terrible overdrive resonance sound.
Not voice 1-5 only voice 6. Could it be a faulty voice card ? Otherwise it sounds great when turning the res. down on the HP filter. It only occurs on voice 6 at the max res. HP position and cutoff between 10-11 ?? Strange. Low pass filter got no issues.
Thanks for any ideas. I have tried all of the tips and tricks, troubleshooting guide. 

[cube48]

Is the patch Poly or Unison?

I sometimes encounter similar issue with some self made patches (can't tell what my HP RES is at that moment) when inputing MPE data (channels 2-6) but the patch is Unison. When I play that patch with normal, non MPE MIDI input on channel 1, all voices get reset to the same sound/parameter setting. If I then switch back to MPE input, issue is gone, all voices sound the same. To me it seems as if some residual MIDI value is off for one voice.

Maybe try to push through all the voices while wiggling (resetting) the Mod/Pitch Wheel and/or Pressure and switching Unison on/off. Or feed it filter MIDI CCs from some external source while rotating voices.