I don't know if it's related, but this is very similar to an issue I'm seeing with Izotope Alloy 2. In a mono track, I see a maxed-out fluctuating level in the right channel meter. The left meter doesn't show anything. It may only happen when the saturation effect is enabled in Alloy. Perhaps the Console Emulator's crosstalk is causing whatever is going on in the right channel to show up in the left?
I have been assuming that the issue was because of the way Sonar doesn't have "real" mono tracks, as is also shown in the way it uses the same UAD dsp on a mono as on a stereo track.
I will see if the issue with Alloy has any correlation with 64 bit engine. I need to do a bit more work to figure out the Alloy 2 problem, so it might be different anyway.