Periodically my Roku will have no sound at all. It happens randomly and the only way to get it back is to pull the Rokus power and plug it back in.
I have my Roku connected to my tv and than a sound bar connected to my tv via the ARC hdmi cable. My sound bar is a TCL Alto 8i my tv is an Insignia Roku tv but it stopped getting software updates so I bought the streaming stick.
I really don't know why this keeps happening but nothing but pulling the power on my Roku gets the sound back. I really just wanted to write this as more of a bug report cause I really don't know where else to report something like this.
Hope this helps or maybe someone even has a solution! Thanks!
Don't know if it will help, but try disabling the Power Saving Feature implemented in OS 10.5 for the 4k/4k+ devices. (Settings/System/Power/Power Savings (20min) - Uncheck to disable).