Everyday we have to power down and back up soundbar pro otherwise blank screen, it is plugged into hdmi arc port of 5 plus year old Phillips tv
It works fine once rebooted but loses communication to tv when not using . When powering with remot it appears to power up initially but blank screen unless powered down and back up
Roku operating system version 10.5 added a new "Power" item in the "Settings > System" menu for some of the latest Roku devices. I don't know if the Soundbar Pro is one of them. If you have the "Power" option, an "Auto power savings" setting there will put your Roku device into a low power standby condition after a period of inactivity, such as when your tv has been turned off for a while. Frankly, I don't see the point of this.
By unplugging and restarting you are taking it out of this standby condition and returning it to normal operation.
If your Soundbar Pro has the Power option in its Settings > System menu, go into it and deactivate any power saving option you find under "Auto power savings" to keep it from going into the standby state in the first place.