Vicky, I understand that you've used your Nexus many times, but there is no such thing as "linking your I-94" to anything. An I-94 is now only issued if you cross by land. You make it sound like one is committing a crime by using the term "getting caught". People don't cross the border on their own, they get "admitted". The moment there is a slight problem with any aspect of your entry, CBP will stop you for an inspection, Nexus lane or not. The 6 month entry will count from the date of your last date of entry, regardless whether it was a stamp, I-94, or -in my case- neither.
Here's a good example that will interest you:
My most recent entry stamp is May 03 (so my stay would be until Nov 03). I stayed 1 night, came back, and flew to the US again on Jun 01. At YUL, for some reason CBP just didn't feel like stamping my passport. I asked for it but he said no need. I insisted by explaining that I needed a full 6 months to stay, and with an irritated tone he said "I just gave you 6 months". A few days later I checked my online entries and, indeed, the Jun 01 entry was there. My point is: whether you are entering using Nexus, Global Entry, Sentri, Fast, or EDL, they are admitting you based on the date they see in their database. Of course, glitches happen and they may ask for a hard copy every now and then, but that doesn't put you in a dire situation where you and Escobar are treated the same way. I cross twice a week using 2 bridges. When I cross way before sunrise and the only 1 regular lane is open, I have a quick chat with the same guy who's in the booth and I learn more about the process with each visit.