Cubase Stock Reverbs Bug

Hi, I think I found a bug in Cubase’s stock reverb Plugins (except REVerence).
When I use them on a 5.1 channel, the plugins works fine with that channel count.
But when I pan the objekt (linked panner for the send) in the very middle, the reverbs adds no reverb to the signal anymore while they do at any other position. It is just the dry signal left.
Only with REVerence that problem is not occuring.

I add a screenshot, showing the level of the channel that is sending the signal and the level (none) that e.g. REVelation ist giving out.