I have the TV Samsung UN50DU7200, Sony h1-xt1 soundbar, Roku model 4850x with software version 14.0.4.12222. The hook up goes as is:
Soundbar -> TV(eACR)
Roku -> TV HDMI 2
I have to have the roku directly to the tv because the soundbar does not support the full function of the soundbar. So I can't use the eACR port from the tv to roku. How this works, the roku outputs the picture and audio to HDMI 2 on the tv, and the tv outputs the sound from the eACR port to the soundbar. Not only does this output the sound but with the IR from the roku remote lets me control the volume and power on and off the devices.
As for the Alexa issue. This has been working perfectly for months now. I could say, "Alexa, Roku on," and the soundbar, roku, and tv would turn on. As for the roku the white light on the front would be off and now it would be on, white and see it flicker a bit. I can give the command, Alexa, roku off, and everything would turn off. Even the white light on the roku would go off.
I have not narrowed it down yet, but at least after a hour, if I ask alexa to turn on roku, nothing happens. The light does not even come on nor flash. I have to press the power button on the roku remote to get everything off. Once I do this, Alexa now can control roku. I can turn everything on and off, pause, play, start apps, volume, etc. But if everything sets off for say minimum a hour, roku will not respond to alexa. If all is on, I can say roku off and all goes off. A few minutes later I can say, roku on, and all turns on. But wait a hour and you have to use the remote.
I removed the roku app from alexa and reinstalled and still the same thing. I have several other roku streaming devices and it seems to be the same issue with all of them. If they set to long with no activity, alexa can no longer turn them on.
So I am not sure if an update to alexa, the app, or the roku started the problem. I do have one older roku device that is a different software version and it works fine when I hook it up. I have 4 streaming roku device and this is a problem with 3 devices and the 1 is fine. Almost seems to be a software issue between the roku and the alexa app skill.