I've had an HS210 wired and working for more than 2 years flawlessly with one dumb 3-way as a partner. I've used them for a several hundred watt spotlight outside. Now, the smart switch no longer works. When I switch the dumb one, the light goes on and the smart switch light goes off correctly. When I turn the dumb on off, the spotlight goes off and the smart switch correctly shows it's lit ring. However, the smart switch does not work physically nor through the app. I tried restarting and resetting the switch without success. I took a look at the wiring behind it and everything appears to still  have a fine connection. What could be wrong?