Please use this document as a resource to troubleshoot your Red Series Dimmer Switch. We'll list out generic issues you may encounter during installation that are not hub specific. For hub specific issues, please click on your hub below to be taken to that troubleshooting page.
Home Assistant - ZHA
Home Assistant - Zigbee2MQTT
The easiest way to find your issue is to look at the Table of Contents located on the right side of the screen (on desktop) or via the drop-down at the top (on mobile).
Switch No Longer Controls Physical Light (But Remote Control Works)
If you're having an issue where you can't turn on and off or dim your Red Series Dimmer Switch from the wall, but you can control it via your app (SmartThings, Hubitat, Home Assistant, etc) and, if applicable, your Voice Assistant (Google Home, Alexa) then likely the local control feature was inadvertently enabled.
To fix your Red Series Dimmer switch not being able to turn on the lights via a button press, simply press the config/favorites button (top right of the switch) 8x rapidly. The LED Bar should flash green indicating Local Control has been restored.