Actually all three nodes were constantly displaying flashing streaming messages for over a day (with the entire flow disabled)... I just wasn't paying too much attention at the time while setting up another Blue Iris Server.
It wasn't until I started taking the cameras offline, when working with Blue Iris, that the nodes gave the red "not responding" msg. I can't recall for sure, but I think they went back to the blue "streaming" message when the cameras came back on line.
Also... and I have no way of testing this anymore as I have since deleted the flow to keep those little ESP32 cameras from being overwhelmed by too many client calls, but after copying those nodes to another flow, when troubleshooting for this topic, the issue turned out to be non-reproducible.
So somewhere, somehow, I suspect that entire tab/flow was compromised during all my prior days of testing and experimenting with nodes and styles, leading up to "producing" my final results that I had posted here.
In the end, we have an unsolved mystery... but probably not one that will make it to any historical status 
