Harmony screws my snapshots

Harmony VST with Ableton 12.
I have an audio trac where I placed a copy of the lead vocals and I have an instance of Harmony.
I set the source to silence and the harmony to 0dB.
I created three snapshots:

  • number 1 is empty
  • number 2 with two voices left (pitch -5 pan -50 level -7) and right (pitch -5 pan 50 level -7 formant -1)
  • number 3 with four voices (-5 / -8 / -12 / +4) spread from left to right and with different levels.
    In Ableton I created an automation envelope to change the snapshot at different point in the timeline.
    It happens that here and there, the content of the two used snapshot changes by itself. For instance, the left voice of snapshot 2 goes to center; or a couple of voices of snapshot 3 changes their pitch, and sometimes position: any clue? And any help?
    I have this settings:
  • generate notes from the input = OFF
  • note mapper = OFF
  • chords map = OFF
  • key and scale are greyed out
  • in each snapshot the correction to the scale is off
  • there are no mods assigned to controls. There is only A1 assigned to the level knob when no voices are selected but it seems I can’t unassign that.
    In Ableton I have only the envelope that changes snapshot number (I mapped the snapshots knob so I can automat it).
    Hope someone can help.
    Thank you.