Creating a VCA fader totally messed up my routing - why?

Hey everyone! Longtime Cubase user here (almost 25 years) experienced a weird bug today so bear with me here for a sec. Today I selected all of my drum groups and drum send effects (my drum send effects are always pre fader) and applied them to a new VCA fader. Everything looked good and all faders were responding as they should. It was not until I pressed play that I noticed the whole balance sounded TOTALLY OFF.

At first I could not figure out the issue and looked at volumes but eventually I discovered that many of the drum tracks either deleted their fx sends or even moved them to different slots - so from slot 1 to slot 5 all of a sudden. YES, this really happened. This cost me hours of time troubleshooting and now I am afraid of using VCA faders again.

Any ideas as to what could cause this?