Start with dependencies
Ask whether the controller, network and target device are all available.
Separate manual control from automation
If the device works manually, the problem is likely elsewhere in the logic path.
Check recent changes
Router replacement, firmware updates, account changes and moved sensors can explain sudden failures.
Simplify before rebuilding
A minimal version of the automation can reveal which condition or action is breaking.
Keep in mind. Compatibility is not permanent. Confirm the current manufacturer, platform and certification information before purchasing, resetting or migrating a device.