I will try this, but I have set display to not go to sleep for an hour in the System Settings, Energy Saver, Power Adapter. Yet the display still turns black and the unusual thing is that when I click the touchpad or touch a key, the screen turns on, I have to log back in, which is normal, but the Roon program has to be restarted, which is not normal. Typically if a screen goes to sleep, when it is awakened apps that were open before sleep are still open.
Will let you know if the fix you’ve suggested solves the problem.