Inserting a Soft Synth Changes Other Soft Synth

Hello--
 
This is strange and very irritating. I have a project where I have Session Drummer on one track. It's been in the project since near the beginning of when I started it--no problems.
 
I added a new soft synth track last night and well into the project and it took me awhile to figure out how the SD track was no longer audible--but I could see it was receiving MIDI data. I poked around and then saw that the OUT of the SD MIDI track was now pointing to the IN of the newly inserted soft synth (kontakt 4).
 
The SD track is receiving on MIDI channel 10 and the new soft synth was channel 1 and not even contiguous to the SD track. Why did this happen? Fortunately the fix was quick but far from painless. It really affected my workflow (and my peace).
 
Any ideas?

Seth [DAWGURU]
I've seen this on numerous occasions where instrument outputs will change like that. Its a bug AFAIK, and might have something to do with control surface routing, but I'm not sure.

Thanks for the reply. I'm not using any control surface.