When I use ‘MIDI Notes’ mode in the VoicePrism, the panning of some voices varies depending on what notes are coming in, and to what voice the unit assigns to the note. With different gender settings on the harmony voices, this is especially noticable.
If you set the harmony mode to "Harmony notes mode four-channel" (under the vocals edit button) your voices are assigned to the designated MIDI channel and the three channels above this number (it wraps around…ex. Select ch. 15, use 15, 16, 1, 2).
The MIDI files can then be authored with specific voices in mind, and with specific pannings in mind. If you don’t want to go to four MIDI channel control and want to avoid the panning and gender ‘jumping’ effect, pan all voices exactly the same and have all other settings including Gender the same also.