T'shooting Problematic Smart Switch

[manimalism]

I wired a MOES (brand) 3-way smart switch at a desired location in my home and set-up the thing within the SmartLife app. Mechanically, the 3-way switch works as expected; and I can toggle the smart switch ON/OFF within the SmartLife app. So far so good; however...

Two problems within the SmartLife app:
1) the app displays the switch as online but always OFF; and,
2) the app will turn ON the switch as scheduled but it will not turn it OFF when scheduled.
The SmartLife app reports all is good with the switch. So, while I can control the switch remotely, I have no idea if the lights are on or off and automation isn't possible.

I’ve done the intuitive t’shooting whatnots with no change within the SmartLife app:

• confirmed wiring is correct;
• confirmed distance-to-router is not a factor;
• re-paired the smart switch to the SmartLife app;
• relocated the switch to the other end of the 3-way circuit;
• disconnected ground a/o load from the switch;
• swapped the affected switch with a known-good MOES 3-way smart switch I currently use elsewhere in my home;
• replaced the problematic smart switch with a new MOES 3-way smart switch.

I also connected a different brand smart switch at the same location. Result: SmartLife app displays the switch online but always ON (?); and the same scheduling problem.

Interestingly, when I bench test the smart switch in a 3-way configuration, the SmartLife app displays the correct ON/OFF switch status, and ON/OFF scheduling works! This confirms 1) the switch works properly; and 2) the SmartLife app is getting accurate status information from the switch. This also suggests the hot a/o neutral wires are the culprit? ...like maybe noise across either/both conductors causes a status sensing issue that the switch’s CPU broadcasts as errata to the SmartLife app? I don't know how to test this theory nor how to detect noise in the 3-way wiring.

SmartLife and MOES email support provide zero useful assistance with this matter so I'm on my own here. I should post my dilemma in home automation forums, but perhaps someone reading this post can offer some insight.

[machinist]

You've done very thorough testing, and your results strongly suggest that the problem is related to the wiring or electrical conditions at that specific location rather than the switches or the SmartLife app. The key clue is that everything works perfectly on the bench but not once installed in the wall. One likely cause is a poor or shared neutral connection. Smart switches rely on a clean neutral reference, and a high-resistance or floating neutral can cause the switch to work mechanically and respond to app commands while still reporting the wrong status. You can check this with a multimeter by measuring between hot and neutral, which should read around 120 volts, and between neutral and ground, which should be under 2 volts. Higher readings may indicate a neutral problem. Make sure all neutral wire nuts are tight and that the neutral in that box belongs to the same circuit as the switch and the light.

Another possible issue is voltage backfeeding through the 3-way travelers. To check this, turn off the breaker, disconnect the load wire, and turn power back on to see if the app suddenly reports correctly. If it does, there may be feedback through the travelers or the companion switch. Verify that your 3-way wiring matches the manufacturer’s diagram and that only one side has line power. If possible, try installing the smart switch at the opposite 3-way location to see if behavior improves. The ON-but-not-OFF scheduling problem could also come from incorrect state sensing. If the switch thinks it is already off, it may ignore an off command.

It is still worth testing with incandescent bulbs to rule out LED compatibility issues, although this seems less likely since your bench setup worked. Electrical noise on the line is another small possibility, especially if other devices or motors are on the same circuit. Because these steps involve working with line voltage, make sure the power is off before opening any boxes. If you are not comfortable handling live wiring, hire a licensed electrician to safely check the neutral and traveler connections. Overall, the issue seems to be caused by the electrical environment at that location, most likely the neutral or 3-way wiring, and checking these areas carefully should help you find the root cause.