Thanks for the reply!
So, the issue is repeatable in that if I go to "insert new instrument", it defaults to omni/none, which then has the newly created track accept input from other midi tracks (seemingly random). The same goes for adding just a basic midi track. If I select just my midi keyboard as the midi input from either the dropdown on the "add new instrument" dialogue, or on the midi track's input dropdown, it does not do that.
If I select my midi keyboard as the input in the "add new instrument" dropdown, it will persist as the default choice for the remainder of the time I have Sonar open, but it reverts to omni/none when I re-open Sonar. I have also tried changing the input on the "add new instrument" dropdown to my midi keyboard, adding an instrument, deleting said instrument, verifying that the next instrument I go to add has my midi keyboard selected as the input, and then saving as my template, but when I open the template, the issue persists.
I am trying to figure out how to change it's default input because as I'm sure is evident, it's pretty annoying that every time I add a new instrument or midi track it accepts input from the other midi tracks.
I also apologize if I'm not understanding what you're asking, I've never had to get too deep into midi signal chains and all that, so this is right at the high end of my pay grade and I might be missing something obvious.