Appreciate the help in advance.  I've installed a number of HS210 with success, but I'm having an issue with a new one I just installed.

When the 3-way switch is turned on from either the HS210 or the Lurton Diva dimmer, the light flickers then turns on.  It turns off without flickering.  I tried disconnecting the HS210 from the Kasa app and setting it up again, and then the light constantly went on/off.

Does this mean that I need to swap slots for the switches?  Only issue is that there is no neutral wire in the other box.  Could it be a loose neutral?  Haven't tried the one spare HS210 yet to see if I have a bad switch.