I have a Sonoff R2 successfully installed in HE using most the most recent Tasmota. The device works perfectly in the HE Dashboard, including showing the current status (on or off).
I've successfully added this device to my Alexa Echo and can also turn it on and off using voice commands.
However... When I ask Alexa if the device is on, it says it's 'not supported by this device'.
Also, the device has three capabilities: