Aeotec switch not responding to ON/OFF command

An Aeotec smart switch is no long responding to ON/OFF commands. The lights are stuck in the “on” position and can only be turned off at the breaker. The switch is hardwired into an attic junction box and has been working consistently for about 4 years. It is still reporting the energy usage, but will not turn “off” with either the iOS ST app, Minimote, or IFTTT commands.