Hi again.
VO stands for Voice over not video output. This issue hasnt anything to do with video .
I think that its possible that the Voice over on your Premiere timeline may be out of phase, and therefore any playback of an outputted file WHEN PLAYED IN MONO may miss the voice over from the mix.
So my suggestion was to ensure that any VO (voice over) on your premiere timeline is only 1 side of the vo file. This means it will only come out of 1 speaker. Then this track needs to be panned to the centre to output it through both speakers, and increase its volume by +3 db to make up for the panning (fade law). The VOICE OVER can no longer be out of phase as you only have only 1 leg of it on the timeline.
Hope that makes more sense.
Let me know
Peter
Post Production Dubbing Mixer