I'm sorry to hear that, have you tried the following below?
Yes but unfortunately still not working. When I say "Alexa" the Soundbar responds as if listening and all 5 LED lights come on. Then it does nothing. As if it's mute or having a problem responding. Any suggestions?
Can I have your current firmware version you should be able to see it in the smart things app.
Also just to confirm you are using commands such as these?