Oh. Oh my god. What. What?? Guess who just randomly figured out how to make it work? At least it LOOKS like it's working with no consequences now?
So I did some more testing today. More moving around plugin load order to see what worked. And I found out that while Status Construct (this plugin) WAS causing the Passive States to break, what seems to have caused the Status Construct to break was an entirely different plugin! So I went through trial and error, reorganzing ALL of my other plugins to find the culprit, and it was CGMZ Unlimited Event Conditions of all things??
So what I did was as simple as placing VisuMZ Skills & States Core on top, Synrec Status Construct under that, and CGMZ Unlimited Event Conditions on the bottom, and now Passive States and Configured States both work at the same time.
Thank you so much for all your help. I am still stumped, but at least it looks like it is working right now.