All I can tell you is that NI plugins have frequently screwed up my channel configurations when used as inserts! Worst offender: Guitar Rig. I don’t know if it’s the way I’ve had it configured or what-- but my experience is that it has a nasty tendency to turn my stereo tracks mono.
Not what you’re asking about, but maybe related somehow. It’s been enough to keep me away from them. Love the VSTis, but haven’t figured the plugins out yet. Nor have I been able to come up with a reason why this should happen, in any case.
Good luck,
Chewy