Roku operating system version 10.5, which is currently rolling out, has added a new "Power" item in the Settings > System menu for some of the latest Roku models. In my estimation, these power management options don't work very well.
If you have a "Settings > System > Power" menu item, under "Auto power savings" see if deactivating "After 20 minutes of no interaction" fixes the problem.
Roku Community Streaming Expert
I am not a Roku employee, only a user like you. Please, no support questions via private message -- post them publicly to the Community where others may benefit as well.
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