The Roku sound when first released only controlled tv's by hdmi-cec, still only control the tv volume by that. But it was found out that many tv brands won't awaken from standby via cec signal like they do for IR commands. So the roku was updated to allow you to power the tv by IR, go into:
settings> remote & devices> remote> remote in USE> program tv> follow prompts to program the tv power by brand.
Before anything refresh the cec devices in your tv settings, see if that helps first.
Edmund
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