Cubase8 routing stereo channel to mono group panning problem

Cubase 8 routing a stereo channel to mono group.
Using the panner on the stereo channel I would expect that I can control which portion (left or right, or a subtle mix of them) would get send to the mono output. It does seem to work - sometimes… When I save the project and re-open it, despite of the stereo channel panner setting, I here both L+R or sometimes even the opposite of the panner setting appearing on the output of the mono group. in this case the panner doesn’t make e difference anymore when changed in value.
I need to re-do the routing settings again to get the desired panning control again.
I encountered this of for e first time in Cubase 8.0.10.