I have the following configuration in my garage.

3 gang box with duplex outlet, 2 pole light switch, and a 3 way light switch.

The duplex outlet and 2 pole switch are on one circuit breaker with a GFCI outlet in this circuit.

The old 3 way is on a separate breaker.

I put the HS210 in place of the old 3 way switch. But I had a problem when bundling the HS210 white neutral in place of the old 3 way white neutral that was in the box. When I connect the neutral from the HS210 to the same neutral bundle of the old 3 way the GFCI tripped.

So I tried to connect the HS210 neutral to the neutral bundle of the duplex outlet and 2 pole switch. (can the neutral from another circuit work?) This seemed to work.

The duplex had power. The 2 pole switch work to control a set of lights. The HS210 had power indicated on the front of switch.

So I went through the setup procedure with the app. During the setup I tried to manually turn on the HS210 to see if the lights worked. No success. I thought it might just be due to the HS210 not being "setup" yet. (Will the HS210 turn circuit on/off before going through the setup procedure?)

The setup seemed to work. I bypassed the setup of the second switch. (I am planning on using the second HS210 in a different place in the house.)

But the HS210 does not power on the lights either manually or using the app.

When using the app to power on the lights the indicator circle turns power on (green) for 10 seconds and then back to power off (gray) indication.

The second 3 way switch on this light circuit is a traditional 3 way switch located in the house.

Now it does not work either.

I believe the old 3 way switch was the first on in the 3 way circuit. It is closest to the breaker box.

Bottom line of problems:

(1) GFCI outlet trips when the HS210 neutral is connected to the neutral bundle of the old 3 way switch.

(2) When the HS210 neutral is connected to the neutral bundle of the other circuit in the 3 gang box the HS210 gives indications of working but doesnt control lights.

(3) Can the neutral of another circuit be used in place of the neutral of the old 3 way circuit?

(4) Will the switch manually power circuit on/off before being "setup"?

Thanks for any help I can get