Check the net standby settings for on or off and try setting the timeout stand by to the max. It may be going into standby mode automatically.
So I looked at all the settings again and I’m not sure I see the settings you are talking about.
Can you be more specific about the actual wording of that setting? The only “timeout” setting I have is the one I mentioned before. It’s the one which powers the amp down after the preselected time. I was warned it is bugging and will often shut the amp off in the middle of listening to music. It’s set to “off”.