Blue-series Multi-way weird on-off behavior

I’ve got one switch that’s in a 6-switch multi-way setup (7-way? No idea what to call it at this point - Mostly the previous house owner’s obsession about being able to turn off outside lights from anywhere in the house). Wired using dumb toggles, and the Blue series in the line box, with a neutral.

In one “configuration” of all the dumb switches, the Blue series works fine at the switch, on and off work as expected.

In the other “configuration” of the dumb switches, the blue series always reports “on”, regardless of the actual load state . If you try and turn it off at the blue series, the relay clicks, and the status LED goes dim for a short bit (less than a second), then turns back on. The load actually switches though (if it was on, it’s now off, if it was off, it’s now on).

Video of the weird behavior: https://photos.app.goo.gl/FmiCiq9FQRWrvJk1A

Total wire length is estimated at ~120ft from the Blue series to the last dumb switch. Might be some level of inductive / capacitive issue with so much wire, triggering current sensing somehow?

The 3-way next to it (a standard 2-location 3-way setup) works fine.

Which hub are you using?

What is the load?

Using habitat, 2.08 firmware. Switch is configured for one-off, not dimmer.

Load is 2x LED br30 bulbs (75W equivilant, dimmable), plus 2x outdoor dusk to dawn motion fixtures (which I hope to replace soon) with 60W equivalent non dimmable LED bulbs

Just a guess . . ., the motion sensors are causing the issues. Can you easily take them out of the loop i.e. unwire them and test without?

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Going on vacation for the next few days, but I’ll try that when I get back.

Not sure how that would cause issues though - Why would it work right in one configuration, but not the other. (Like when the lights are on the load terminal its OK, but when they’re on the traveler terminal they’re not? I’m not sure which terminal works right, and which one is wrong, could be the other way around) - Maybe some weird parasitic load with the motion fixtures combined with some difference in the 2 terminals on the switch?

Yeah, it could be a lot of things. I understand what you’re saying about one terminal or the other, but a smart switch is more complex. One thing we’d see with the Reds is that they won’t work in multi-ways with lighted dumb switches. I can’t explain technically why that’s the case, I just know that it is.

So I’m thinking that the motion sensor may be the same sort of outlier. But this is just a guess on my part.

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(Background: I’m an electronics / firmware engineer for my day job)

The lighted 3-way switches cause issues because they draw some power, even when the end light isn’t connected - Essentially the switch can’t tell the difference between the 3-way drawing power and a low wattage LED.

The motions here I wouldn’t expect to cause problems, since they’re completely disconnected when the loads are off, but who knows what weird behavior they cause on the load side, so it’s definitely a good diagnostic step - Essentially eliminate anything weird in the setup.

I may also try just dropping another blue series in place here (or even a red, I think I’ve got one spare) to see if they have similar issues.

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