I have the same issue where Alexa responds with "<devicename> is not responding"
Has there been any solution to this issue? The sonoff switch that is on 1.5 works. The newer one of 1.6 is not working correctly with Alexa. At first, it would not discover it. When it finally did it reported issues. Both work in the Ewelink app. I created an IFTTT command to control them as a workaround. Was getting ready to install a bunch of these in my mother's house this coming weekend. But if they dont work with alexa I will hae to pass.